If the West Coast states (minus AK) became independent...

[Pessimistic Antineutrino]

i) What do you think the name of this nation should be?

I know Cascadia only applies to Oregon and Washington but I think it could work.

ii) Where should its capital be?

I would have to agree with San Francisco. Maybe split it off from CA and make it its own district like DC, but it would probably stay part of CA.

iii) What would be the major political parties and who would be its first president?

Probably still Republicans and Democrats, but if those states actually seceded then there would probably have been new parties formed before secession.

I could see one of two things happening with the parties:
Either the Republicans moderate heavily and become competitive, or they eventually collapse and the Democratic Party splits (or a new party forms) after a period of dominance. The former is more likely though.