Multiple SP in multiple IDP Clusters with SAML?

I've not tested this yet, and it may rely solely upon the SP we're using, but here goes:

I have two NAM clusters.

One for internal, one for external. Soon we'll have a third one (one for a third-party Identity Provider).

Let's say I configure all three NAM ID clusters to have a trusted SP. We run the trusted SP on some other server in our LAN.

1) I am assuming that because I have 3 distinct NAM IDP Clusters, and thus 3 distinct SSL certs, that I'm going to have 3 distinct metadata sets that I will have to send to the SP?

2) I am also assuming that the SP will ALSO have 3 "things" (for lack of a better word) in it, each correlating to my ID providers, and thus, I'll have 3 distinct metadata files from the SP?

Am I on the right track? Has anyone setup anything like this before?

--Kevin