All of my living room's home theater equipment is roughly 10 years old, including a commercial 50" Panasonic plasma (monitor only, no speakers), an Onkyo HTIB speaker set with sub, and two Onkyo receivers (one for the TV, DVD player, cable box and HTIB, the other powering a set of outdoor speakers around my pool).

Problem is I'd like to add a Fire Stick or Roku for Netflix and my plasma only has a single HDMI input and my receiver has none. I'd like to get rid of the mess of component cables, optical cable, and RCA cables that I've got running from the receiver to the various components.

I've been out of the A/V loop for some time now. What features should I look for in new equipment with regards to HDMI inputs, 4k capability, THX, etc.???

I would need support for:
TV
Receiver (if necessary)
DVD player
FireStick or Roku
Cable box
Outdoor speaker set with independent volume control