I'm just trying to get my head around the rules to do with production...

Basically, if I own a Starport with my RMs inside it, will I be able to use them when I want to build from a Factory without the RMs being inside the Factory?
Or will I need to move the RMs into the Factory?

I was able to use materials located in other factory in the same city in production, so there shouldn't be big problem. Especially you can transfer them between facilities.

If the storage building you are using is in the same city as the factory, you will be golden.