They should stay at the top most of the time as they like to establish a territory in the upper layers. It's usualy the males though. BTW, it's not usualy a good idea to keep them in pairs as one will tend to bully the other - trios are better (one male, two females). It can be tricky to tell what sex young ones are but males tend to have pointier and larger fins than females and are more brightly colored. When in good condition, the males turn a dark color on their ventral half.
Kissing gouramies need over 30 gallons to be comfortable and grow very quickly. If you don't have somewhere to put them now, return them to your LFS and get some once the tank you are planning is actualy ready for them. Note that they'll also devour plants and, once grown, can eat very small fish.
RTBSs and albino sharks will fight once mature.