What would you estimate the grafts per cm2 to be given photos provided and is this optimal for fine hair? (photos)

You cannot tell how many graft were implanted based on photos alone.  If you are concerned, ask your doctor.

30 grafts per cm  square is a quite good density .. But no one can tell you that how many grafts have been implanted to your scalp with just looking at photos..First regrowth should be observed on 3-3.5 months. Regrowing hair is thin, undersized and not bright untill 4-5 th months of hair transplant. İt's normal for new growing hair starting to get native characteristics, waviness, curl in first 6-7 months..This actually takes 10-13 months for hair to become full mature , as thick and bright  as native hair. 

It is impossible to estimate the density of the grafts after a surgery because shedding occurs.