i know, but keeping them in the tank will stunt them and eventually kill them.
the problem with keeping them to re-home them 'when they grow too big' is that they wont. In a way it's true when people say fish will grow to the size of the tank. However it will do them massive damage, they will becomes susceptible to disease and will die far too early and in a horrible way.
To be able to spot when they have reached they're max size for the tank is nigh in impossible so really it's best to re-home them now before any damage is done.
sorry that's probably not what you want to hear but i know you want to do whats best for the fish and in this case to re-home them asap is the best thing for them.
yup your right, you can see underneath them with both the platys and swordies they have a gonipodrium (sp) which basically looks like a willy, so you can tell if they're boys!
a BN Plec is a bristlenose plec, they're like your plecs but IMO cuter and only grow to 6" so you can have one for life in your tank.
cories are corydoras catfish, very cute little buggers, stay small at 2/3" max and are the friendliest funnest fish