Problem with that idea is that never in that house's 130 year history were the spindles anything but a painted finish. And the same is true for every other Victorian house. That said, the primer is the most important coat, and it should be brushed into the wood. how you get it on the wood is your choice; you could paint-pump and brush in, or roll on and brush in. The spindles could also be dipped in thinned primer and hung to dry, catching the drips with a brush. With cedar, oil primer is de rigueur Casey

I prefer to spray cuz I'm lazy :) But I do understand the overspray issue can be difficult and if it's not a huge area, you can easily do a brush, you just have to work a bit harder. You might look for a sash brush, which is nice for nooks and crannies...it's a round brush that comes to a point in the middle, kind of like a pencil does (if that makes sense) verses being flat or flat with an angle. If your metal is basically flat, you can easily roll it. I always just wire brush, and if it's just a little bit by hand isn't a big deal. The sanding is to smooth out your wire work if you have to do a lot of it. If the rust isn't bad and you don't go nuts with the brush (scraping up the iron) You won't need to sand. Primer is something I never skip. It's your long term fix, and many good primers seal well so you would be sealing the metal from future issues, but that said, rustoleum is a great paint for this type of thing and seems to hold up well. I've done metal with and without primer and while the primer jobs always hold up long term much better, the rustoleum alone holds for a few years if the initial problem you're fixing isn't a bad one. Be sure to go beyond your rust areas about an inch or two on all sides as rust is one of those tricky things that can hide in areas near the actual "wound".

If the squirrels are gone, I would sand lightly, fill any deep holes with wood filler and repaint. If the squirrels are still around, I would not bother to repair the railing.

Trying to maintain the simple lines of the existing structure. Remove gable and use same roof material everywhere. New roof extends to existing ridge. Columns smaller. Remove additions around garage door. I'd ask for a drawing showing no shutters under the porch, and correctly sized shutters shown too. https://www.lifeofanarchitect.com/residential-architecture-101-shutters/