Welcome back!

Healers will always be needed, so don't worry about not finding your healing services required and greatly appreciated by tanks like me. In the 2.1 patch an addition to the Duty Finder called 'Duty Roulette' gives bonuses for undertaking a dungeon randomly selected by the DF depending on the least popular class role that is seeking - this is usually either a tank or a healer, so there is definitely incentive for sticking with SCH or WHM.

As for your FC question, sadly I play on a different server, but a good way to find FCs and lses recruiting on Gilgamesh would be to check it's server forum, found here: http://forum.square-enix.com/ffxiv/forums/826-Gilgamesh