No shame in buying a starter AR, pretty much everyone (here) has done it at one point or another...and PSA is a decent source.
At any rate, yes, AR stuff from different manufacturers tends to be compatible with other manufacturer's stuff...but there are many many exceptions as the market has grown over the years and companies have stretched the market beyond standard 'mil spec' stuff for various reasons. Regarding the spring noise mitigation ideas presented in this thread, so long as you get the variant that is for collapsible/carbine stock-style receiver extensions (aka "buffer tubes), then you're good to go and it should be completely compatible. Checking the web site of the manufacturer prior to buying whatever option you choose, just to be safe, check the manufacturer's www site.