first time - solo traveller

okay. so I'm doing the london/paris/rome your in november and I'm panicking a little. I have alot of questions.
I would love it if someone could help me out.
and sorry if any of these are repeats

1.)do we just bring our suitcases to all our locations? I read something about leaving luggage in the contiki basement and bringing overnight bags...
2.) how much is recomended spending money for food. I'm alright with just a sandwich or whatever for lunch. and same with dinner.
3.) exactly what kind of accomadation am I to expect?
4.) how much luggage is recomended (i thought maybe 2 jeans, 3 or 4 shirts (includes fancy shirt), 1 skirt, 1 dress for night out, 3 shoes (walking, fancy, flip-flops), whatever required undergarments :P, some kind of coat (i'm assuming a wintercoat is a good plan. maybe my light jacket.) and some other things..)
5.)how many optional excursions are there? are there more than the ones listed?

I can't think of any more questions right now. If I think anymore I might explode anyway haha

Thanks