Where's aridas sofia? I believe his speculative/alternate Phoenix had an accelerator 'gate' that it had to pass through to go to warp, which in turn led to later ships with the 'ring drive' which led to sets of rings, i.e. nacelles. From what I can remember of it I quite liked his setup, and I don't see why it couldn't have been modified to fit the FC scenario. I don't remember how, or if, he suggested it would be orbited.
I'm sorry. I just saw this post. Here is a brief little outline showing some of what you mentioned.
Size comparison of various testships and the giant negative energy induction ring they are launched through. This giant ring will later shrink to the point it can be carried along (ringships) and even later, carried within nacelles (coils):
Here are the various testships shown in silhouette above, including my take on Phoenix
And here is how the ring gets incorporated early on. This is Valiant
And a very early Earth Star Fleet ship from the 2090s:
When I draw a nacelle on these early ships, it is a rocket -- the nacelles are M/AM rockets, the conventional impulse drive. Fore and aft are hypergravity containers that hold microsingularities, and for the ships with rings, amidships there are the warp rings that hold open the wormhole created by those singularities. The habitation module is tucked safeli at the center of those rings. For ships without rings, there is the big, stationary warp ring to get you going. If you fall out of warp before you get back, you have a long haul home from the Oort Cloud on impulse.
As you can tell, I was heavily influenced both by Jefferies' early art and contemporary speculation on how a warp drive might work.