[katello] Katello as Relacement for Satellite (Smart Management)

I know there are already a couple of posts about this topic but hopefully
my query is something that hasn't been asked yet. At least I couldn't find
anything about it during a couple of quick searches.

I see that Katello can generally be used to replace Satellite server but I
have a couple of clarifications regarding that:
a) What does the Red Hat "Smart Management" add-on really provide and would
it still be needed if using Katello?
b) Does Katello support any other *nix platforms besides those in the Red
Hat family (RHEL,CentOS,Fedora)? I found some vague references but this all
seems to hinge upon subscription-manager which seems to be a Red Hat
specific tool.