Villain is in SB and is a big fish with 43/0 in 80 hands played.

Here, at the flop with my TPTK i've decided to bet 1/3 pot in order to take directly some value without my opponent fold if i bet too expensive. In this kind of situation i think that i take showdown equity from all combos except AA (which would have been 3bet preflop) 88-55, but these represent only few combos.
First question : Is my sizing right in order to prevent my opponent fold but to take value ?

Here with the 4h i think i've always the lead because sb check first so he can't represent a pair of 44, he could have hand like Ahxh or Kh8h but these hands need 11 outs to take advantage so he has something like 25% equity
not to mention its eventual blufsthis, this is why i bet 3/4 pot.

Here at the river, i'm facing a donk bet from small blind, only few combos beat me : 66 (if he would have 88-55-44 he probably check/raised me at turn), 97s, 23s which represent hands which he would not seem play preflop, so i decided to call here and he had 97o.
My question here is to know if my way of playing this hand was well, and even if SB is a fish, to take into acount hands really weak preflop to make my decision