In general, I don't place too much importance on naming my characters. Often as not I pull them out of a database after shouting 'Boo!'. But as writer, we can use the opportunity to make the name plot-relevant. I.e. if a character is named after a prominent figure; if she has a name that other kids use to bully her; if his name is starting with 'Z', always last to be called in class;...
Not personality, exactly, but I tend to go for names that suit their role and character. Heroes tend to have heroic-sounding names, villains tend to have cool names that sound good when shouted while standing on top a massive doomsday device, that sort of thing. Mostly I'm just looking for the right sound: It doesn't need to have any deeper meaning, I just try to find names that have an appropriate ring to them, if that makes sense.
Depends really, but I don't focus too much on matching name to personality, but what fits the character. Use name sites to get the best possible fit, when writing exotic and foreign names. Sometimes they fit the meaning behind the name, but otherwise give weight to the plausibility of the character being more fleshed out on that front. For sci-fi, it is kinda tricky, since I have to literally cook something in the old easy bake noggin from scratch that doesn't sound too stupid (I hope) for the reader to not laugh at my lack of alien type-ish names. If you really are in a pinch, I suppose you could try a naming generator that cooks up random names by the genre(s) of story your writing. Good luck, and I hope you get your naming issue resolved in some fashion.
I can't really start writing if my MC doesn't have a name. I tried just working with MC once and it sucked. Usually, I tend to go with a name that has a "ring", leaning towards strong sounds. I had a Gabriel Stone once and a guy called something-or-other Diamond, though admittedly that was not-to-be-published porn and unfinished crap, respectively. Currently, Eddie Sterling is doing very well. Then for other characters I often do sort of tributes. I've got a guy who gives off an undertaker vibe called Mr. Plana. The thought process: undertaker -> death -> grim reaper -> Tony Plana did Manny Calavera's voice in Grim Fandango. They're not all this convoluted...
