Starting out with this unit definitely feels like you're opening Pandora's can of worms, but as you go deeper into the rabbit hole it starts to make more sense. You just need to keep digging (and forget the left turn at Albuquerque) and you'll find the treasure.
Leon details a great method for finding good sounds, which he suggests for finding Cab IRs, but would work well for a lot of your editing, actually: use the looper to record a bit, then tweak things until you hear what you like.
For the cabs, set focus on the cab number picker in Axe-Edit and use your arrow keys without watching the screen, so you can focus on HEARING the cab rather than reading the cab names. I found I generally prefer the ribbon mics. When you find one you like, bookmark it with one of the colors and you can later filter by color to find all your faves in the cab list. Might be good to color good cabs for clean amps with one color and good cabs for dirty amps with another, or American one color and British another, or some other distinction you might find useful for grouping them. The cab list is GINORMOUSLY HUGEANTIC. The filters are your best tool to find things quickly.
You can also filter by name with the search tool - great for finding all the ROOM IRs, which are a great add-in spice for helping the main IR sound more like a real amp in the room through your FRFR rig. The room cab can be any one of them, too. It doesn't need to match the main cab. Currently I have the room cabs on my presets around 13dB down relative to the main cab, but you might like more or less room than I do. Play with the time alignment of the room IR, as most are MPT (minimum phase transformed) and the room IR may sound better with a little sliver of delay to phase-align it a tad *after* the main IR. You can look at the first big hump at the left end of the impulses and dial the room one until its peak is just a bit to the right of the main cab's peak. You can also play with the "air" and "room" parameters in the other tabs in the cab IR config, but I am liking just a bit of a room IR seasoning the main cab sound. Adjust until it sounds good, basically, and, ickety ackity oop, the treasure is yours....
