1) One great way to deal with phase issues is to use something like the Little Labs phase tool to basically shift around the phase of the second mic till you get all you want out of the combination
2) I wouldn't aim the SM57 at the centre of the speaker. Better to do that with the ribbon mic. Use the SM57 towards the edge of the cone or a bit further away and pointed in towards the centre.
3) Refining does change how a profile sounds, even if it isn't necessary. Usually I'll do a profile once and then save, then profile again and save after refining.
4) As far as multi-mic profiles, the Kemper definitely can handle more than one, but the results will depend on how you position the mics. In that regard, it'll be good if the monitoring system in the studio is up to scratch, because what you put into the Kemper is what you get out of it, even if you can't always hear it.
1) Thanks for the tip!
2) I guess I'll play around with the mics till I begin hearing what I like
3) Believe it or not, I had thought of doing exactly this!
4) Yeah I think the monitors are fine. A bit bass heavy to my liking, but I was planning on adjusting the control room sound a bit in the first place...
Thank you nightlight