On the galvanic corrosion issue. I did 5 years in the Navy working as an Aviation Structural Mechanic on H-60s. On that aircraft 99% of the airframe and structural components is Al. In a salt water environment (deployment) anywhere that anything but Al touches it for the most part one of the two parts will corrode. The way we get around that is for the most part just paint. All I know about the paint that was used was that it was a poly based paint. However the only place that we had to be particularly careful was around the engine bay and the gear box mounts.
For the gearbox mounts the issue there was an Al frame for the aircraft and the gearbox casing was magnesium. Yes the metal that burns. They way that corrosion issue was solved was a combination of a special anti-seize and a stainless sacrificial plate. More of a shim really as it was probably in the realm of .020 inches thick.
In the engine bay the heat shield on the engine side was a thin layer of Ti. Now Ti does have a galvanic reaction with Al. The way around this was to install a layer of stainless steel between the Ti and the Al. What this did was split the difference between the galvanic properties of the Al and the Ti. End result in the area was zero corrosion.
So based on this I believe that the best way to prevent any galvanic corrosion would be a combination of things. First and foremost, prevent any physical contact between the brass and the Al. Not sure if anodizing would fix this as essentially anodizing is just a chemical conversion of the surface layer. It is not adding anything new to the surface of the substrate. My personal suggestions would be some sort of heat cured paint like an automotive style or something as simple as a single layer of electrical tape. The reason I am suggestion the electrical tape is the process at which galvanic corrosion occurs. In addition to this stainless screws could be used.
Actually I just did a search on wikipedia and according to the chart toward the bottom of the page and the limits in the paragraph above it, you should be good between Al and brass. For those that want the link it can be found
here.
Just my 2 cents from a high school drop out.
Melvang