Seat Runners and bolt questions

Removed the seats yesterday to fit some protective edging round the crotch strap holes (to stop fraying of the belts), but came across several different bolt types.

Passenger seat:
Front = 2 x 6mm hex cap head 15mm bolt - TVE 12.8
Rear = 2 x 6mm hex cap head 15mm bolt- SEP 12.9

Drivers seat:
Front = 2 x 5mm hex button head 25mm bolt - (no markings)
Rear = 2 x 6mm hex cap head 25mm bolt - SEP 12.9

Q1: Should they be all the same type of bolt?
Q2: What’s the difference between the SEP/TVE ratings?
Q3: Are they the correct type of bolt?
Q4: If not what are the correct type?
Q5: Do I need cap head bolts (lower profile)for the front drivers to allow clearance for the adjustable seat rail?
Q6: I have a drivers crotch strap that was secured under the rear bolts which I guess is why the bolt length was 25mm not 15mm as in the passenger side. Could I get away with 25mm bolts all round, or is the mounting holes not deep enough?
Q7: I’d like to swap the rail round on the drivers side to give more forward movement (so Fi can reach the peddles better). I know I will lose the same in rear adjustment, but I don’t have the seat right back anyway. How do you swap these over?
Q8: Would there be any issues with scraping the side sills if the seat was able to move further forward

Think that’s enough for now, cheers

From memory that’s exactly what I found (bolt size and length wise) when I took the seats out of my car (S1 Exige). So I guess it’s normal. As far as your other questions go, no idea.