[Prosites and Ultimate Branding] Multisite Plugin Load

Hi,

I am planning on a SaaS solution using wordpress. Actively considering Pro Sites and Ultimate Branding, had a few questions?
1) Do these plugins need to be network activated - I am guessing yes?
2) How heavy are these plugins in terms of resource intensiveness?
3) How many subsites can these plugins handle?

Looking forward to your response.

Thanks

Best,
Avinash