Hey Cocoboy - sorry for the delay in responding,
You'd be ok adding one yellow tang to a 75 gallon tank but I'd not have more than one.* They can be territorial and will slap at each other with the spines they can stick at the base of their tails.* Only having one tang is my recommendation and you can keep other fish in the tank with them since they are mostly aggressive with their own kind.* They should get along fine with clownfish.
There isn't a whole lot to choose from when it comes to schooling saltwater fish that are commonly available.* However, do a google search on Chromis cyaneus (blue chromis) and Chromis viridis (green chromis) which I think are schooling saltwater fish that should get along ok.
Look here too -
http://www.fishlore.com/profiles-blue-chromis.htm
http://www.fishlore.com/profiles_blue_green_chromis.htm
If you want gobies - check out the Elacatinus oceanops (neon blue goby). It's a cleaner fish but it should also accept frozen, live and flake foods.
http://www.fishlore.com/profile-neon-goby.htm
You're at the really fun part in my opinion - researching the fish and inverts.* Spend more time at the beginning and you'll have less headaches and more enjoyment going forward.
Mike