An angel means no corals,,but you can keep things like mushrooms and rics..
You can only keep one ,,2 are likely to fight..Should be the last fish added..
Flamehawks ,clowns,royal grammas,firefish,most wrasses ,cardinals and a lot of types of anthias will be good starter fish that will be good in a 75
QTing is a good thing
Grow your filtration