[SH] Questionable preflop, horrible, horrible turn, and a scary river bluff

Misclick fold nuts is....painful.

It's good vs thinking players at higher stakes, and you can overbluff this spot at NL16-NL25 I'd say as long as you bet smaller on both streets, you represent QQ+ (KQo) very well here,and people expect you to cbet most your air. However vs unknown at NL5 I'd prefer to do it with my AJo combos only personally (along with AA QQ part of my KQo -KQo is fine to split between cbet and check behind otf) as we remove AK, and JJ combos (JJ will call more often than lower pocket pairs) and the J is a better out for check behind that the 3 ofc. And people at this limit call down pocket pairs on paired boards too much in general.

I'd cbet flop with AXs with a backdoor flushdraw, so this hand as well, and barrel those 10 flush outs
and check fold AXs without one

don't forget to balance your misclick range though

Randomly misclick nuts...

As to bet sizing, I made it about 61% turn and 71% river. Is that too much? Is the default in 3-bet pots 50-60% as opposed to 60-80% in normal pots (depending on the board texture)?

Your sizes are ok. You fulfilled your goal.