What does this simple rebus mean?

What brings you down but never up?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

There is an exact a week gap between Christmas and New Year. Hence, It is obvious that the new year that comes right after Christmas comes on the same day of the week.

A Strange thing happened in the Year 1777. Christmas occurs on Wednesday and New Year on Monday. How is that possible?

What is common among 11, 69, and 88?

Can you complete the sequence?

192, 021, 222, 324, 252, 627, 2__, 9__?

All of you like to eat me. I am a five-lettered word. Remove the first two and I turn into an infamous animal. Remove just the first and I become a heinous crime. Remove the first and the last and you can groove on me.

Can you guess who am I?