I just had the issued amount, didn't get any extra, and 2 years later everything is fine. These things really don't matter too much. Although I was stuck wearing dirty/used shirts to morning PT sometimes. Get a couple extra shirts and shorts I guess. I never really wore compression shorts, so I don't know about that. Never really chafed during indoc, although I know some people did.
The way it works is you bring all of your bags to the gym and leave them there with your name and company. They are later taken to your company storage area, and you get them back around when indoc is over, unless its stuff you need during indoc such as medication, toiletries, etc. So you don't really carry that stuff all day, like people say.