Using Z-net on HS3 and Z-troller with HS2

Ok,
So I broke down and purchased a Z-Net for my new HS3 system as the Z-troller worked inconsistently. The question I have is, as the Z-troller works fine with HS2 and HS3 is on the same system sharing all the other I/O devices in common - is it possible to delete all the Z-wave devices on HS3 only and start with a clean slate using the Z-Net. However, if I need to, I want to be able to fall back to my HS2 system and the Z-troller... (hopefully I won't have to). I wonder if this is even possible as I don't know if my stat for example can actually pair to two separate interfaces..:confused:
So is it possible to delete all the Z-wave devices in HS3 only? If so how would I do that?

A couple of other basic questions...

1) why does the Z-Net have USB ports? Are these for real?

2) I see the mention of the Z-Wave+ app for Android, but I don't see the app offered on the playstore.

Thanks,

Rob