That excludes me. But I'll try anyway
3 tracks is not overkill. At least as long as you are experimenting and often that helps to find a suitable way forward. With more experience you might reduce this easily when having more confidence in the result then. I usually do at least 2 tracks via SPDIF: Git dry and Stack. Sometimes I capture the signal with stack but without cab via analog input in order to put other IRs / Cabs on it in the DAW. So many ways to find great sound...
That's a good one. The more gain the more need to tame the high end. I always use high cut and low cut with each profile. But I tweak them on a profile basis, initially with headphones and then in the rehearsal room if they are meant for live use as well. Often I go down to even 7,5 or 8khz and up to 100/120hz for the low cut. For recordings that can be quite healthy and you can easily try the effect within your DAW as well and then transfer it into the Kemper.
Finally: It's all a matter of taste but even with high gain recordings I tend to use reduced gain, especially when double tracking. Some say you shouldn't do this... but as always there are many ways to come to your sound...