I should activate WHMCS Multisite at all network, or only in one site, or it makes no difference?

And about this other functions:

Domain Mapping – Sell domain names and have them mapped in for you with our Domain Mapping plugin!

No Restrictions On Sites – You can sell sites on as many WordPress installs as you wish, you might have hundreds of them, or you might let our Multi-Domain plugin handle all those extra domains for you on one install.

I should to install this others plugins too? To make thins functions works? Or this functions are the same of this plugins and are embedded at WHMCS MU provisioning plugin? tks!