At the beginning of the game....
Mon-el rushes in to smash Doomsday w/ a generator. With the PC of Dream Girl, he gets a critical hit. So Doomsy should take 7. Oh, wait a sec.......maybe just 2

Just got the fig. , anyhow...does his special power (DD can use Invulnerable/stop turning when Unstoppable appears.), does that apply to the first hit he takes?

Don't see why not. Hit him hard enough, and he stops on that special power, kinda like the wheel on the Price is Right. :D

Why wouldn't it?

The only way to get past it, is with Pulse Wave. That's the only way. You can get past the second click of it by Outwitting it if he lands on the first one. But who plays a figure like that without a Fortitude card?

Does the disruptor device work against doomsday's special power?..think the special power says something like stop clicking and the disruptor prevents damage reducers from working

No it doesn't, because just as you said, the SP doesn't reduce Damage, you just stop turning the dial.