Aragonite is the best choice for sand. If you get crushed coral, you won't be able to keep sand-dwelling animals and it can lead to water quality problems down the road when it gets clogged with crap.
I recommend the Aqua C Remora Pro for a HOB skimmer. I think it's the best HOB out there.
And I used to have those 48" Nova Extreme T5 lights. Very good lights. Go for it.