Welcome!
I have a RXA3060 that I use the internal amp for rear surround duty, with external amps for the front L,C,R. Until you find value in a dedicated processor or preamp, make use of at least some of your receivers amplification, particularly for rear or height surrounds - you'll save money with a 5 or 7 ch amp vs 11ch.
The Monolith amps have been getting great reviews, but I also can speak to Emotiva as two UPA-1's have been flawless for almost 10 years now with our heavy usage. See what kind of good deals or post Independence day sales you can find - or wait til Black Friday.
An
RCA Y Plug will allow you to connect two subs, but you will need to measure the SPL at your listening position(s) and adjust each sub individually.
I also advocate power protection, such as an
APC H15. We live in an area that sees lots of power fluctuations with constant construction and what not. The H15 uses an active relay to monitor Over and Under voltage so all connected components are always getting exactly what they need.To me, its cheap insurance and I just lost the first one after 7 years - once the relay goes, the unit is toast. Hot tip - make sure you always turn it off before plugging or unplugging anything!