My choice would be the .270 Winchester.
-Very popular, almost every rifle manufacturer makes them in multiple configurations. Same goes for ammunition.
-Already a mild recoiler which could be mitigated further if necessary.
-Flat shooting for setting up maximum point blank range.
I always have and likely always will. All of my rifles are more accurate than me anyway. I put the savings toward good glass, good ammo and components.
Sno Seal is largely beeswax with other natural additives for longevity. I have a pair of LaCrosse All-Temp boots from the late eighties or early nineties that are still as waterproof today as they were when purchased. I attribute that largely to Sno Seal.
I still hunt whitetails in the southeast (Bowling Green KY is as far north from FL as I hunt) and I could never keep my feet warm, regardless of the amount of insulation in my boots or the combination of liner/sock. I started to apply unscented anti-perspirant to my feet and that helped a lot...
I think you answered your own question. Work on the basic fundamentals until you can diagnose problem areas and improve your shooting skills. Get some instruction if you have to. Without perfecting your shooting skills, diagnosing equipment needs will suffer. Newer or better equipment will not...
My feet sweat terribly, regardless of liner/sock/boot combination or material I've tried over the years. I began using unscented anti-perspirant on my feet. It definitely makes a noticeable difference.