Knutty, you are better to contact me directly to get answers. But to answer your question, as silanarchy said 15 numbers is ideal, not essential. But if you can cover all 15, it can make a big difference in many cases.
With either the lite, hybrid or uber versions, you can have multiple people receiving predictions. ie one player covers one set of numbers, and the other covers other numbers. The lite and uber default equipment (2 player) support 2 players receiving predictions - each player can receive different numbers. The hybrid can support many more. There is more to it but I cant discuss that in public.