I'm 18, and tomorrow a couple of my friends want to go to the gym, it will be my first time working out in an actual gym, I only plan to use the treadmill this time. I use to be skinnier (125lbs) a couple years ago, I am now more like 180lbs. I'm just wondering what I should wear to the gym that won't show off my stomach? I was thinking a slightly baggy t shirt and some "comfy" black pants.

Do you think this will be too hot?

Another thing is, I don't leave my house without wearing full makeup (foundation,eyeliner,blush)
Should I bring something like oxy pads that will remove my makeup before working out so I don't get acne from sweating?