You may twist or untwist twist ties on Jewish festivals (and Shabbat), but only if you intend them to be a non-permanent seal.

We are required to eat two meals on Jewish festivals, each preceded by kiddush, one in the evening and one in the morning. For both meals for each Jewish festival day (and all three meals on Shabbat), say ha'motzi over two complete loaves of bread, each of which is at least 1.3 fl. oz. in volume. 

Source of Saying Jewish Festival Kiddush
Some kiddushes are commanded by the Torah (d'oraita); the others are from Chazal (d'rabanan), as follows:
Kiddush d'Oraita

• First night of Jewish festivals
• Night of seventh day of Passover
• Night of Shmini Atzeret.

Kiddush d'Rabanan

• First day of Jewish festival
• Second night of Jewish festival
• Second day of Jewish festival
• Seventh day of Passover
• Eighth night of Passover
• Eighth day of Passover
• Shmini Atzeret day
• Night and day of Simchat Torah.

Source of Jewish Festival Kiddush Location
Saying Jewish festival kiddush at the place where you will eat your meal is a rabbinical (d'rabanan) enactment.
Jewish Festival Kiddush-Meal Quantities: Evening

• For evening kiddush for a first-night (d'oraita) Jewish festival, a minimum of 4 fl. oz. (119 ml) of wine must be blessed on and at least half must be drunk.
• For evening kiddush for a second-night (d'rabanan) Jewish festival, a minimum of 3.3 fl. oz. (99 ml) of wine must be blessed on and at least 2.0 fl. oz. must be drunk.
• For the evening meal, as on the first two Shabbat meals and for all required Jewish festival meals, a minimum of 1.9 fl. oz. (56 ml) of bread must be eaten within four minutes.

Eating Requirements for Jewish Festival Morning Kiddush
There are two separate eating requirements during the daytime. They may be combined (say/hear kiddush and start the main meal right away) but are often done separately (say/hear kiddush and then eat some light foods and beverages; the main meal is eaten later in the day).
Note Since eating and drinking requirements on all morning kiddushes (both Shabbat and Jewish festivals) are d'rabanan, the required beverage amount for morning kiddush is only 3.3 fl. oz. (99 ml) instead of the d'oraita 4 fl. oz. (119 ml) (which is required for kiddushes for Shabbat evening and all first-night Jewish festivals).

• Morning kiddush requires a halachically legal “meal” with these elements:
  • Blessing on a minimum of 3.3 fl. oz. (99 ml) of wine (or other beverage),
  • Someone's drinking at least half the beverage, followed by
  • Eating at least 1.3 fl. oz. (39 ml, or 1/6 cup) of some type of mezonot within four minutes. 
    Note If you drink at least 3.3 fl. oz. (99 ml) of wine within 30 seconds, you do not need to eat mezonot.
    Note You do not need to drink the wine or other kiddush beverage to fulfill “establishing a meal.” You may hear kiddush and then simply eat the required amount of bread or mezonot. This applies to Shabbat or Jewish festivals, evening or morning.
     

 

• The real meal (kovei'a se'uda) requires eating at least 1.9 fl. oz. (56 ml) of bread (or matza during Passover!) within four minutes. It must include enough food to satiate. 
  Note You can simultaneously fulfill the requirement to “establish a meal” and to “eat a meal” by eating one (the same) piece of bread.

The minimum attire required for saying blessings or studying Torah is shorts for men and a covered torso for women. But more of your body may need to be covered due to location and circumstances. For example, if men are in view, women's tzni'ut rules take over since they are more restrictive.

Eruv walls must total more than 50\% of the eruv border on each side, so that most of the expanse of the eruv is enclosed, either by an actual wall or by the form of a doorway (tzurat ha'petach), with no gate or gap over 10 amot (about 16' 8”, or 5 m) wide.
Note  In order to count as part of a border for a private domain, any doorway, gateway, archway, etc., must be intended to be a doorway, gateway, archway, etc.--and not there merely for decoration or function (as in supporting something above).
 

When Tish'a B'Av begins on Saturday night, the custom is as follows:

• Say baruch ha'mavdil when Shabbat ends. 
• Say the blessing on the candle after ma'ariv.
• Do not say the remainder of havdala at all. Instead:
  • Wait until Sunday night, after the fast is over, and then
  • Say only the blessing on the wine and the paragraph of ha'mavdil blessings.

You may not salt certain foods, whether cooked or raw, on Jewish festivals if the:

• Foods have a shell, such as corn kernels (on or off of the cob), beans, peas;
• Salt has not been heated previously (such as during salt processing) and the food you are salting is hot (over 120° F, or 49° C); or
• Salt will materially change the flavor of the food, especially if it causes a chemical change, as when salting cut or chopped onions or salting tomatoes.
  Note You may dip the tomato or other food into salt using your hand as long as you eat the food immediately afterwards.

Note If the food has oil in it, you may add salt even if the food contains onions or has a shell.

Say she'hecheyanu when eating a fresh (not dried or frozen) fruit for the first time it appears in the market that season (this does not follow Rosh Hashana or any of the other Jewish “years”).

SITUATION
You have a fruit on which you would like to say she'hecheyanu, but you might not like it.
WHAT TO DO
To avoid saying a pointless blessing (bracha l'vatala), you may:

• Say the blessing borei pri ha'eitz on a different fruit.
• Eat from the fruit you just blessed over.
• Taste the new fruit. If you like it—and before you have eaten all of the new fruit—
• Swallow the small piece you tasted (if you do not like it, you do not need to swallow it).
• Say she'hecheyanu.
• Finish eating the new fruit.

NoteWhen saying she'hecheyanu on a new fruit, there is no preference for on which fruit to say borei pri ha'eitz--you may say it on the new fruit or on any other fruit.

The halachic category of dairy and meat errors, while extremely complicated, has many conditions for which leniency may be applied. Here are the main points a halachic authority (posek) will need to know:

• Was the food or utensil hotter than 120° F (49° C)?
• Had the utensil been used for hot food (over 120° F) within 24 hours?
• How much food was involved?
• What was the relative volume or quantity of the food and utensils? (1/60^th of relevant volumes?)
• How much food is normally cooked in the utensils?
• Of what materials are the utensils made?
• Was the food spicy (hot peppers, garlic, onions, lemon...)?
• Was the food needed for Shabbat meals?
• How much does the food cost?

 

If you are outside techum Shabbat (which may be as little as 0.7 miles, or 1 km, past the last house of an inhabited area—city, village, etc.), you may start Shabbat at sunset even if the nearby community starts early, as long as the rabbi from that community does not have authority over your area.
 

Havdala is said after Shabbat, Jewish festivals, Rosh Hashana, and Yom Kippur.  Shabbat havdala is more extensive than after Yom Kippur and Jewish festivals. 

Shabbat havdala consists of:

1. Beverage: Wine, Grape Juice, or Chamar Medina
   Wine is always the preferred beverage for all havdalas because it is prestigious.
2. Spices
   The extra soul we are given on Shabbat leaves after Shabbat is over, so we sniff a pleasant odor to cover for that loss.
3. Flame  
   The Shabbat havdala flame commemorates that Adam HaRishon (the first man) created fire after the first Shabbat.

To make a car into a sukka:

• Open two doors on the same side of the car and put schach on top/across the doors.
• Make sure the doors reach to within 10 ½ inches (26.7 cm) of the ground or curb (so you might need to park at a curb).
• Make sure the schach over the doors is at least 40 inches (1 m) above the curb.

 

Ritual impurity (tum'a) in a cemetery comes from being within 4 amot (7 feet) of a grave. This is horizontal distance, regardless of how deep the body is buried.

One person per household should make an eruv tavshilin in order to allow cooking on a Jewish festival for the next day, if the next day is Shabbat.  The person sets aside something cooked and something baked and says a formula (which can be found in most siddurs).

You must say borei pri ha'gafen if you want to drink wine (or grape juice) after you heard kiddush and then:

• Spoke without drinking any amount of kiddush beverage, and/or  

• Spoke before the kiddush leader drank at least 2 fl. oz. (59 ml) of wine (or grape juice) from his cup, and/or
• Heard someone make kiddush over a she'hakol, even if you drank from that cup.