[Sonozaki]

Sorry for all the questions here, but I'm puzzled on a few things. All help is appreciated. (Keep in mind that I quite literally understand no Japanese whatsoever, so please respond in English.)

- Let's say I want to negate the adjective aoi (blue). To do this, I simply change the word to 'aoku nai' (not blue).

Now let's say I want to negate the adjective taisetsu (important). What would I change to express the word as 'not important'?

- Another issue regarding negation, except this time with verbs. How would I express the words 'kuru' and 'suru', as 'not kuru' and 'not suru'?

I'm guessing I do something along the lines of changing..:
Kuru to Kunai
(or..)
Kuru to Kuranai
..but I'm not sure. Can anyone clarify?

- Lastly, what does the particle 'to' mean? Here's an example sentence:
Dare o korosou to shite iru? (Who are you trying to kill?)