Your drive code is somewhat strange. Do you want a hand with that?
Doing an ffd8 save to a seq file is odd. Just use @:filename when you save and you do automatic save with replace. No ",s". As long as the disk isn't full there is no side effects with that on a near empty disk. All anding and oring before storing to $01 is also useless. Do 35 for ROM out and 37 for ROM in, and you are perfectly fine.