I will add just one last thing, basic is what you make of it and it is all about attitude. You WILL get beat, I'm sorry that is what you signed up for, but no one said basic is required to be the worst 6 weeks of your life (although it can be), yes it will be tough, but if it was easy everyone would do it. Just think, you get to spend 6 weeks with some of the best friends you will ever have creating memories you will always remember. You do have some power over basic and that power is that you can make those memories full of fear and depression, or you can make those memories full of teamwork and hilarious experiences (that even your cadre laugh at). From my experience, it is much easier to remember and laugh about the positive experiences rather than the negative.
Well, I have said enough about that. Thanks for the questions to get us back on track.
I can't remember if they were considered contraband, but if you do bring extra underwear, make sure they are white and you might get away with it.
As for the cold during basic, don't worry about it. You will be up and working out within minutes. Yes, I felt pretty cold in when we first got up some mornings, but when you go work out for an hour, you are usually pretty glad that you didn't bring any extra clothing. As for wearing something different, that won't go well unless all of your classmates look the same. You must always standardize with your classmates or you will be asked "Why are you different, basic." They will give you enough clothing and they will also tell you what to wear in the morning. "Bang, Bang, Bang, FALL OUT TO THE CQ WITH _______ UNIFORM ON."
As for bringing things, I remember going to the C-store on about the 3rd day. Remember, you will have seconds to brush your teeth, shave, and do whatever you need to do in the morning so don't worry about using everything up. As for using plastic in the C-store, I can't remember if it is allowed. I remember pretty much everyone used cash (Can't remember what they told us about that). Maybe Jezzie can help you with that.
Later,
Brian