First, I am going to move this to the nano section.
Your plans look okay.
1) Light should be fine for some low light corals (discosoma, etc.)
2) Live sand is pretty much a waste of money...eventually the rock will seed the sand. You can also use a scoop from another reefer's tank to seed dead sand.
3) I would look for nano-specific powerheads as they are small in size but move a lot of water. I have heard good things about Azoo.
4) Salt is expensive because it is purified and enriched for specific use in salt tanks. Buy it in the big buckets for the best deal.
5) Two percula or ocellaris clowns would be a good option. Damsels will not be a good option. Cleanup crew should go in first.