VERY GOOD QUESTIONS
The gaskets are updated or a different manufacturer. They will work fine.
The bolts are "stretch bolts". They have a starting torque spec that is just before the stretch. As you torque them with angular rotation, they will stretch and give a permanent torque setting. The best way is to torque then paint a small dot on the 12 o'clock position. Then you will know which ones you have done 90 and then 90 again.
I don't use any sealer on the head bolts that are not in an oil galley. I just clean the head and the threads then dip in oil.
No sealer is required on ANY of the gaskets.
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS