Recently Razer have introduced the Razer Turrret , while I don't usually recommend their products however this product surely meets your needs as you can use it on the sofa.
Video Link : https://www.youtube.com/watch?v=vjtwtCpsdGs
I'd recommend buying something from Cyberpower as they focus more on gaming and can be upgraded in the future . Or Build one yourself which will be much better in handling games.
Yeah it will run , just don't overclock heavily as the PSU is made of cheap capacitors and can fail under load.
You'll be fine otherwise :)
Expected Wattage : 380W For the whole system.
I'd pay for the MSI Dominator , even if its 2x8 gb which is overkill however it'll stand the test of time and probably won't need any upgrades for a while.