Best room treatment

The worse the room, the greater the advantages of the Swarm. Do that first, then wait and see. Odds are you won't need any bass traps. 

As for panels, find a local hardware store that will sell you a couple sheets of Owens Corning 703 insulating panels. They're what GIK and everyone else wraps inside their fancy acoustic panels. In raw form the panels are ugly yellow but very light weight and dirt cheap making them a perfect way to experiment and determine what (if anything) you need, and where.  

Diffusion panels are a little more involved. But remember, everything in the room is either reflecting (diffusing) or absorbing. You could hang framed art on the wall, tilt it down slightly, you got a diffuser.

I will consider strongly making them myself as my WAF financial tank is running on fumes. I have another question in regards to bass swarming. What is the probability that one or more of the subs will end up in a bad spot like out in the middle of the room to get the best sound ? 

A couch preferably fabric, some pillows, a carpet, a chair or two preferably fabric, curtains, a tapestrie, a coffee table, an end table.....a picture or two or three....you know, a regular lived in room, jmo. No ugly crap in my listening room. 

Does the swarm system work equally as well for home theater and music listening? I am 90% HT use and powerful, room shaking, chest pounding bass is what I’m looking for. I currently have a single Seaton Submersive with dual opposed 15” drivers. I have no room treatments, but use EQ via Dirac Live.  I am very intrigued with the thought of trying this system.

Great question which I was going to ask as well having just read that the swarm method is designed for 2 channel listening and not for HT.