You really can't sex them until they spawn. Angels can be quite territorial when they mature, this aggression is usually directed towards other angels, or fish that look like angels, which means anything with longer fins. Being cichlids, they can get pretty nasty. Yes, they will kill other fish.
That's a pretty good size tank, sounds nice. A tank that size leaves you more options than a smaller tank. I don't know what you have for decorations in there, what I would do is get a good size clean bucket, like a 5 gallon utility bucket, fill it half way with tank water, & put the aggressive angel in there. Rearrange the tank decos, plants. driftwood, rocks & such. This will eliminate any territories. If you have any taller plants, driftwood, or other decos, arrange them in a way that they will form a sort of natural divider. If the angel doesn't see the other fish, he will have a hard time being aggressive towards them. Put the angel back in after redecorating.
I don't know how many of the other fish you have, it sounds like a 90 gallon tank. If it is lightly stocked, you could add more fish to spread the aggression. If you do this, make sure you have adequate filtration, and add new fish a few at a time. If you don't have a small quarintine tank, like a 10 gallon, it may be a good idea to pick one up. It's cheaper than having a new fish spread something to a tank that size, a 90 would need a lot of medication.
Tolak