gloves are a personal preference. at the lower levels, lots of people do wear gloves, at the higher levels, most people don't wear gloves. i personally wear one glove, on my "bottom hand", and thats just because of joint problems. the glove gives the shaft that much more girth, and the neoprene of the glove adds that extra little bit of cushioning for my joints. I think i was the only premier paddler in Australia who was wearing a glove, fwiw.
cotton, in general, is a no-no/something to avoid. that includes underwear. ESPECIALLY on wet days. underwear (be it boxers or briefs) will ride up and chaff the living hell out of your crotch area. I dunno, maybe i'm just a bit more enthusiastic in practices (from day one as a rec paddler), but i have no clue how people paddle with cotton. chaffed armpits from cotton t-shirts, chaffed groin from underwear... plus, when cotton gets wet, it gets heavy. cotton is NOT your friend when it comes to paddle sports.
yes, your body is likely to get wet. at any level you paddle at. it can also depend on the people sitting behind/in front of you, and how much they splash.
for my feet, i'm generally OK with just the crocs while in a dragonboat due to the technique we use (swinging of legs/rotation of hips in the seat). when i paddle in a sit-on-top outrigger canoe, i'll wear neoprene socks from MEC ($12 for a pair, replaced every season). for an enclosed cockpit outrigger or for sprint kayaks, the enclosed cockpit tends to keep your legs/feet a bit warmer, so i'll go bare feet (unless its sub-zero weather).
this is a closed cockpit outrigger and
this is a sit-on-top outrigger (it was -10*C that day i was all bundled up
)