Management point in another domain (no-trust)

Hi folks, we have a situation where we would need to install a MP, DP and WSUS on a server that is in another domain to manage client that are in that domain.

I was planning of installing the roles using a service account, import the CA cert from that domain in the Site server. Will there be any issues?

I was reading about the communication between the sites roles and I also notice that the site server have to talk with a domain controller and the management point also have to talk with a DC.
Which DC are we talking about and why it should talk with them.
Does the MP in the other domain will try to reach the DC in the same domain?
Does the site server will try to talk with the DC in the other domain?

I know it's a strange one but it is the only way I manage to get to reduce the cost and be able to managed PCs that are on the other domain.

Thanks!

Mathieu