Before fish- the first critters you add- hermits and snails and such. You can have 1 snail and 1 hermit per gallon- however many you want. If the food isn't available- they will eat anything you feed the tank. I personally like having a HUGE cleanup crew. I just love hermit crabs for some reason!!
2 tangs is possible- just be careful. Usually one tang is recommended, but on the bigger setups, you can have more. Good choice of fish so far. Watch out for yellow tangs- I've heard many people mention how mean they can be. My blue tang is fairly mild.
Do research on your heaters- just read about a tank being cooked the other day. Doing 2 heaters is very smart, but I gonna have to take a guess and say that a 300w heater
could cook a tank on its own- just check on that to make sure- again I'm not 100%. But add a
sump to the equation and you may be alright- I'll let others comment on that. Most reefers stick to 2 brands on heaters that are known to be trusted *so many tanks get cooked* the Ebo Jag which I prefer and the Won titanium. No heater is safe unless you have a controller, but I trust my Ebo Jag and most people do.
