Originally Posted by
eschatological
I mean, a lot of these are answered in the episode.
For 1), I just think it's the product of CGIing a matte blue person. The glow can cover up a lot in, for example, the movie. It's kind of like the blue genie effect from the live action Aladdin earlier this year.
For 2), it seems like Doc just does what he wants. He glows naturally, but it's not like suppressing the glow is a difficult thing he has to constantly focus on.
3) Ozymandias explains this pretty clearly in the episode: He doesn't lose his powers, he merely forgets who he is and that he has powers. Again, looking like who he is, or not glowing, etc, is not some spell he has to concentrate. It's a switch he flipped, he doesn't actively need to be Dr. Manhattan to maintain it.
4) Again, Regina seems to clearly indicate that he's changed - that he's kept Cal's face, after she removes the ring. She's astonished and gratified for that. The implication is that when she met him in the bar, he looked like his traditional, Jon Osterman self. That's why she offered him a bunch of white men to transform into, and he reminded her that he could be anyone he needed to be, so he should be someone she was comfortable with. This is why we don't see his face in the bar, before he transforms into human Cal. The blue-ness seems to simply be the natural expression of Doctor Manhattan.
5) He's simply saying he can't experience his life in the blank spot before it happens. Note that he says that before the chronological living of it. Doctor Cal will probably now have that blank spot filled in, much like he constantly lived his childhood as a human child even though he had no powers back then.
It seems like you just need to watch the show with more attention. These questions were all answered.