HTs are pretty hardy, and longtime survival can be pretty much guaranteed provided you start with a healthy specimen and maintain good water quality. If you are concerned about hardiness, you will probably want to invest the extra time (and money) to ensure that you get a specimen from Australia, as they are widely considered to be far more durable (and beautiful) than their Indo-European counterparts. I can't remember for sure, but I think I remember reading somewhere that Indo Tusks are still largely cyanide caught, whilst the Aussies are not, hence the better success rate, but again I'm not sure about that.
As far as compatability is concerned, HTs are pretty much fine for any FOWLR system. Some aquarists have noted rare occurrences of bickering between the Tusks and large angels/aggressive triggers, but most instances are noted as not persisting long and not involving the sustaining of damage by either fish involved. Additionally, it is also noted that Tusks rarely eat smaller fishes (clowns, damsels, etc.) that they grow up with, so it may be advisable to introduce a small Tusk to your existing system rather than a large, mature specimen.
Good luck. Great fish.