Just found out about this.

My brother was talking to me about this and i hadn't heard of it yet and I'm excited, it sounds awesome. 

One concern i do have though is if the game can still play on older or just bad PC's in general like Garry's mod can be. 

Work as well as gmod - no. Source 2 is a modern engine, he require better system. But the engine is currently being actively optimized, so it will clearly run well on many systems. Targeting PCs for those who don't play anything but gmod  is a dead end; many indie games are more demanding on hardware than gmod .

I also just found out
First thing I did is buy a bunch of stuff 

Good investment

And I'm buying more lol

Yes sir