I handled enough Wordpress websites which take presctiption separate hosting spaces and also have almost all their own plug ins etc. Taking he time for you to have the ability to update many of these, 1 by 1, is not enjoyable. Another factor is I'd really prefer to have the ability to publish to multiple blogs while drenched in once.

Is Wordpress MU my only option? Or it is possible to wordpress plugin where I'm able to admin multiple wordpress sites? Can there be an API for that admin after sales which may be tied into?

Multisite doesn't handle sites across multiple hosts.

Also, a chance to publish to multiple blogs at the same time isn't built-in to multisite.

I understand I have seen a few different plug ins which will manage existing installs at different hosts, however i can't think about what they are called.