Ideally, I will just be running the Kemper split to my IEM and then to FOH. I don't plan to have any other cab with me
...then as long as you are happy with your sounds through a PA, you will be fine. I use IEM's and FOH although I do still take a cab for my band mates as they don;t use IEM's. With IEM's you don't need a cab. I prefer a cab though rather than in house monitors as I can fully control it myself.
As said above:
1) get your basic sounds sorted through a PA type set up at volume - make sure you output is reduced to around -18db and you know which output you are going to be sending to the desk - should be main. Last thing you want is " no, still no signal" and start worrying about output settings.
2) Sort out your "slots" in a performance - I have slot 1 clean, warm clean, Slot 3 main rhythm, slot 4 spacey rhythm and 5 for solo. Once you are orientated with this then its simples.
Then you will be fine!!!
Once settled strongly suggest you look at Morph - I use it on each slot to boost for riffs and add a bit more mid etc.