I don't understand how you say heat won't be an issue with 1000w in a closet that size. OK fine, but if I were doing 1000, it would be 400MH and 600HPS together, preferably on some kind of light mover.

I like to top once or twice, no need to remove any branches that I'm aware of. I like to veg a month or two so I get some weed. I like scrog.

Will 9 buckets fit in there?

I don't know how you're going to fit a co2 generator and bottle, 1000w cool tube, fans, odor control, 9 buckets, a reservoir and everything else you want in a closet that size. I'd scale it back a bit or build something bigger.