In this forum there is
a list compiled by users that links to all known published patch banks. Regarding your other questions, yes, there are some on-board sounds that are useful for trance/club/dance, but since the manufacturers wanted to demonstrate the flexibility of the Virus, they are not the majority (then again you can take sounds out of their original context and create your own sound signature). Nevertheless, since the TI can load Virus C patches, and there are TONS of trance/club/dance patch banks out there made for the C, I think you are covered.