Help me as I travel abroad please.?

This summer I will be traveling to France for 3 weeks with some of my fellow students. I was wondering if you could tell me some info whether incredibly important or not.
Things such as:

~What (not) to wear?
~Gestures that may be inappropriate?
~Possible gifts to bring to a host family?
~Anything else?

Thank you very much for your time and input. Any information would be great. =D

WHAT NOT TO WEAR ???
(you have to remember that Europe it's not that hot during summer, neither that cold in winter.. you should always have a jacket on hand, b/c our wether there is very unpredictable...)

i tell u this cuz im european... ;)

GIFTS???
(Something typical from your country,in this case "U.S",the family will appreciate it)

I lived in Paris for 4yrs + i've been back a few times, wear what ever it doesn't matter just make sure its summer stuff because france gets quite hot and no real inappropriate stuff execpt the obvious like insulting them and stuff

when talking to younger people such as people your own age use the "Tu" form its more casual and they get insulted if you use "vous" as "tu" is more frendly

oh and it's freezing in winter!! if u ever go there then i was there 3 weeks ago..so cold...

and when talking to adults or people in shops/restraunts etc. use "vous" term its more formal and tu is a little rude to them

comfy shoes would be a very smart decision to make, and my mom went all over Europe and has the cutest charms on her bracelet, be sure to do that so if you have children in the future, you can share your memories with them. maybe you could buy a cutting board for a gift. have fun!!!

You wear ordinary clothes. Be conservative. Don't be too faddish, or too exposey. If you are going into churches, they will often ask you to cover legs (no shorts) and shoulders (you can throw on a t-shirt or shawl). depends on the church and their policies.

I don't know any gestures that are inappropriate (that wouldn't be in the US, anyway) though they have tons that you WOULD use, like the one for to call, to have a drink, etc.

Gifts for a host family: try to find something uniquely American that would be difficult to get there, like something handmade, something that represents your state or town. Something they can display. A wall art or table art piece.

Anything else: HAVE FUN!!