GTLazer

Couple of quick points on this:
 
If you use a valve amp without speakers connected, you're liable to break the output valves/transformer; you need a compatible load.
 
You also can't use a cab sim without an amp sim on the Pods. You could use a fairly transparent amp sim, but it would have to be there nonetheless.
 
You could use the G Sharp. You could go Guitar > Pod guitar in > Pod loop out > amp guitar in > amp loop out > G Sharp > Pod loop in > Pod out > monitor/PC (you'll get unavoidable latency if you monitor through your PC, though - I wouldn't recommend it)
That would allow you to use Pod FX before your amp, then again after the G sharp.
 
There are other people on here with much more experience of 4CM than me, so it might be wise to get some of their advice before making a final decision on how to make this work best.

It's not in with the amps, it's in with the EQs.

I ran into this problem with mine as well.
 
It's because the XLR balanced outputs are at mic level, as they're designed to go into a mixer, simulating the signal they would get from a mic'd cab.
 
The 1/4" unbalanced outputs, on the other hand, are at line level.
 
Seems a bit remiss, to me, not to offer a choice. I prefer the balanced out with ground lift, but because I go straight to monitors (not via a mixer), I have to turn everything up to 11 just to get a reasonable bedroom level. Surely it wouldn't have been difficult to give me a choice of mic or line level...

Yep; knob 1, I think. Your options are bypass or mute, but bypass is the default.