Undecided Question

I really don't want to go spending a whole bunch on MAC. It's just you can't have a makeup collection without at least 1 MAC product lol. 14 years old by the way (please don't tell me I shouldn't be wearing makeup, I have horrible acne and until that gets taken care of, makeup it is). So next weekend or so I'm going to the MAC Counter in Macy's because we don't have the actual store, and I don't know if they would have everything that I would like. Do the mac counters have most of the products or just select products? I've never been to one so I'm completely clueless . I've done a lot of research so that I don't end up buying something that's dupable. Here's what I'm hoping to get:
Cleanse off oil
Mineralized Skinfinish natural
Fix +
Rubenesque Paint Pot
Which concealer would you reccommend for combination oily acne prone skin?
And then pretty much after that I'll just get like one eyeshadow a month to build it up gradually. I'm a sucker for eyeshadow So would they have all that at the counter? Another question: What is your god sent brush from MAC? I don't want millions of brushes, just maybe 1 or 2 that no other brand can live up to. Thanks!