Heh. Sounds yaky.
But you can also dig up info on the net about dead bodies shrinking due to dehydration, perhaps even on wikipedia. Swelling and shrinking at the same time is a bit hard to combine, isn't it?
Maybe some body parts shrink and some swell?
Also you have to keep in mind that even if some parts of the body are swelling, it will likely to continue only until the body tissues and skin hold their integrity, otherwise the inner gases that are created due to decompression process would not be contained inside the body, especialy if they are indeed building pressure that would fasten their release.
Finally the vampire's "fountain of blood" explanation seem a bit stretched to me. If body have been dead for a long time, enough to build this "innner pressure", wouldn't the blood stop being in liquid form do to after-death coagulation process?
Ok, I think I should put these matters out of my head for now, or I may have difficulties eating my breakfast.
Answering your question about pretender - I don't think so. ASAICT when your Last province fall, you will join all dead Gods in the Oblivion. There will be no return due to your Last desperate followers sneaking around, hoping to conquer some faraway province and use it as a Last heaven for their forbidden Deity.