the first thing to think about when considering angels is their potential adult size. they can reach 6 inches from mouth to tail and up to 10 inches tall (rough sizes) so a tank of no less than 18 inches tall is where you should be looking. the cute little fish in the lfs soon grow into big adults in no time if properly cared for so dont be thinking they stay small....
if you intend on breeding them then unless you buy a proven pair then its best to buy 6 or more small fish and let them grow up together and naturally pair up. once you have selected a pair sell the others or return them to the lfs. once paired they breed relatively easy and as long as they are the only fish in the tank it shouldnt be long before they can care for the eggs and they hatch. the first few times the eggs may be eaten by the parents but then they will learn not to eat them

the next few batches will be cared for and the parents will fan the eggs to prevent them getting fungus on them. the fungused eggs will turn white and go furry, non fertile eggs will go white but fertile eggs will stay a creamy colour and you will see the black dot in them which is the baby fish. it may take a few attempts but soon you will get wrigglers which are stuck to the same place as the eggs were laid by their heads and after a few days they become free swimming little fry. even at this stage the parents might still eat them but again after a few trys they will learn and hopefully protect them. it might be safer to remove the parents and leave the fry to grow without any risk from hungry mouths. it can be a long learning session for the parents but they usually get ther in the end

mine use to spawn every 2 weeks without fail and after a couple of months i had very good parent angelfish that cared for the fry.
male with fry
female with eggs
also its pretty impossible to sex angels 100% just by looking at them until they spawn you never know. adult males may develop a nuchal hump on the head but not all do..... even if 2 angels spawn they can be 2 females so wait until the eggs are showing that they are fertile before selecting the pairs.
i hope this has been of some help