Hi Poet, welcome to the forums.
I use my Indigo daily, and it's still largely relevant as it still shares a great deal of functionality from the later models.
Seems the Virus sounds are inaccessible from Vengeance-Sound.com website. I believe Incubation 3 was a commercial set, so you may have to contact Vengeance sound directly.
You can store up to eight banks of 128 patches on the Virus Indigo v1, meaning 1024 patches total. The first two banks (A & B) are RAM-based (but are still retained when unit is powered down, thanks to a
CR2032 battery which you may need to change at some point given the age of the unit), which means you can edit and save single sounds to those banks whenever you want. The other six banks (C, D, E, F, G and H) are FlashROM-based, so you can upload full banks to them, but not edit/overwrite individual sounds (unless you save them to slots in bank A or B).
For transferring sounds, I still use an ancient copy of Emagic SoundDiver. Others may use commercial librarians, but I haven't used them.