Hello and thank you for your question, My name is XXXXX XXXXX X will assist you today.No sealant on the gasket as it will burn off and cause a leak, the starter doesn't have to come off but I have removed it for extra clearance, its your call. The stud should come out right tight and lefty lousy, another words counter clockwise to come out. Vise grips will work if you have enough to get ahold off but be sure to soak the hell out of it and work it back and forth till its starts coming out and keep soaking it as you remove it. If its broken flush then yes, you will have to drill it with a 90 degree drill and yes its a real pain in the rear. The best thing you can do is soak the hell out of it and keep it wet while removing it.