1. What combo of overflow/return pump should I use
Are you planning on drilling your tank? Most glass shops will do it for around $15-25 per hole. Or you could drill it yourself, if you look around, there's tons of info on doing it yourself. If your going to go with a HOB overflow, I'd recommend lifereef. As far as the return pump to pair with your overflow, as long as your overflow can handle more water than your pump can pump, you are good.
2 Should I even use a sump or just a hang on skimmer?
IMO, I'd go with a sump. You certainly can do just fine without one, but a sump would be a good addition to the tank. You always hear people say that they wish they had a sump, I don't think I've ever heard someone say that they wish they didn't have a sump.
There are a lot of options out there. Euroreef, Aqua C, Deltec, ASM all make good skimmers, and I'm sure there are plenty of others that I didn't list, that will get high marks from the members here. Sorry I can't be more help here.
4. how big sump and what do I put in the sump
Sump should be as big as you have room for. You can put your skimmer, return pump, and heater in the sump, and you can also section off part of your sump as a refugium.
Here's a good site with info about sumps, if you haven't already checked it out.
Melev'sReef
5. How much live rock and sand
General rule of thumb for live rock is 1-2 lbs/ gallon. It really depends on the type of live rock though. 75 lbs of Marshall Island rock (which is very light and porous) would probably get you close to filling your tank, where 75 lbs of Fiji (which is more dense & less porous) wouldn't get you as far. There's a sandbed calculator on the RC front page. I wouldn't bother with live sand though. You can get a good quality "dead" sand, and seed it with sand from another reefers tank.
6. finally do I need anything else, I know I need the heater but just want to make sure I get it right the first time
That my friend, is a loaded question.
