Welcome!
One suggestion that will save you a lot of time, and get you playing the Kemper faster - resist the temptation to download large numbers of profiles all at once
You'll want to download any "must have sounds" that aren't included - go for it! But, it will take some listening time to figure out if the sounds are already in the Kemper, before you'll know if you are missing anything.
These rigs are like real amps - they respond well to parameter adjustment, so spending a few minutes with a rig that is close to the sound you want may give you faster results than playing more 50 profiles of that amp.
Even just five minutes of playing and tweaking each of the 400+ profiles that are included would be around 40 hours.
If you make a backup file before you start auditioning rigs, you can confidently delete any rig that you aren't going to use. It will always be available in your backup file, if you ever need it.
A five minute listening session with 1000 rigs (the current maximum number of rigs) would take 83 hours, or so. That's an hour a day, for two months and three weeks.
As of the end of April, 2013, If someone downloaded every available free profile, it would take approximately ten months, at one hour a day, to give each one a five minute audition.