Welcome! Others have already given great advice. I'll just throw in that unscented wipes do wonders for cleaning up the crotch. For the rest, just wipe down with a towel and change clothes after cooling down (10-15 minutes unless it's really hot).

The popular wheel size right now is 29 inch / ISO 622mm / 700C. Other than a limited selection, I don't see any problems with riding 27" wheels.