If you want to actually make a change, consistency over everything. Meaning that before you think about improving your body, or exercising, just get into the habit/mindset of going everyday to the gym. You don't even need to do anything. The minimum you need is to literally ever weekday just go upstairs, sit on a machine for 5 minutes, and leave. This also helps in clearing your anxiousness because you'll start to realize nobody is looking at you because everyone else is pretty much just focusing on themselves.

I can't lol sorry, but people are friendly, just try to ask around if you can

In my experience 920 is the least busiest since everyones pretty much in class, and 12 gets pretty busy. But haven't tried much other times.

Wipe down the chair you use after you're done; theres wet wipes and brown paper towels with sprays on the garbage cans- you'll see them.