well, first thing, welcome to 40k!
Telepathy is probaly the best if you want to use the psyker as a buffer/caster, if you plan on having it going into melee it's worth considering biomancy to beef him up.
About the repetition of units, it's more dependant on the actual codex, certain armies have lots of viable units, while other codexes have just a handful (same goes for whole army builds), the list you're proposing can work but first of all you're probably going to concede first blood due to the dual rhinos, they are easy prey for anti tank weapons also i'd change the equip of the terminators to have 1-2 more shields and drop the assault cannon, their job is to be in melee not to shoot, also get a second claw on the ones with storm bolter/claw for the same reason. About the grey hunters i'd play both the units in drop pods since the unit itself wll force the opponent to choose to use his anti tank to get the first blood or to go for the hunters.If you get the points try to fit in a sixth man with missile launcher into the long fangs unit.
The list itself can work, i'd do the changes written above to have it more focused and less easy for the opponent to deal with but if ou already have the models and you're eager to try it on the table it's an already playable force (no ill meanings here, what i imply is that it most probably won't fare that well against a tournament army but against fun lists it will put on a good fight).