Use the nastiest sealer possible when you put it back on, I use 3M trim adhesive on the block side and Permatex on the oil pan side when I do them. Basically the pan is glued on and the bolts line it up
The front pump seal on a automatic transmission is a common fail at age or high mileage. You can our a pint of ATF seal conditioner in to keep it under control for a while. But once they start its usually a downhill slide. A tired torque converter can make it worse as well.
Good Luck!
Dave