Stumbled into this question while searching for games for Family Basic.
While I have no idea what kind of power the systems of the time had, I can tell you this, the original manual for Family Basic V2 (specifically Game Basic) explicitly mentions that you can write directly to any memory address of the console using the POKE function and also directly call ...
Neither, the speed depends on the level, which in turn depends on the number of lines you have completed.
So if you want to maximize your score, then in the early game you want to focus on getting as much score as possible out of each line, then at some point switch focus to preparing for and then surviving the speedup.
from memory 20 years ago, might not be accurate! :p
yes, the speed increases with every level!
some tips since you seem to struggle:
for training you can start in higher levels, so the speed difference is not that high and you don't get lured into getting sleepy in the first levels. there was a combination to start in level 2+10 instead of 2, not sure, maybe ...
The level determines how fast the pieces drop. At level 9 a piece drops (assuming you don't press down) 1 row every 11 frames. So at the Gameboy's framerate of 59.73fps that means it drops at a speed of 1 row every 184ms.
At level 10 it speeds up, dropping the piece every 10 frames. At level 20 it reaches a speed of 1 drop every 3 frames (50ms) and ...