I'm a small shop guy, too (closer to 600 sq. ft. and still too small!). Early on, I tended to do the same thing with big cabinets, but I've changed my ways. Unless it's a modern design where all face frames, internal cabinet sides and fixed shelves are all flush, I'm much happier breaking the cabinets into manageable pieces.
For traditional pieces, bumped out (or in) sections usually look better, and provide way more flexibility at installation time, not to mention the ability to move pieces around in the shop.
Why do you need to wait to order your doors? If you're using design software (or even good drawings), you should be able to trust your drawings and order them up front.
If you really need to separate your face frames and boxes, there are a number of tactics that can help. "Dry fitting" the FFs to the boxes using pocket screws and/or biscuits in the shop and detaching them for transport can work. I've also successfully used "Fixo" biscuits to attach FFs and trim to boxes in the field. The Fixo biscuits are plastic biscuits with barbs that are essentially self-clamping.
I would never brush a finish in the field. I have yet to find a spray finish that brushes nicely, or conversely, a brushable paint that performs like a good spray finish. I've sprayed waterbased paint in the field a few times, but it's a lot of trouble and I hope to never do it again.
Cheers,
Pat