Using the Interlux products ...
I sanded all the old black paint off down to bare aluminum because I wanted Snow White and didn't want any chance of the old paint being visible. I did the boom the year before I did my mast, so it was good practice and I learned that you don't want to skip the step of etching the aluminum with the Interlux product that they recommend before applying the 2-part primer. I forget the exact name of the product but you will find it in their literature. After several years, I have found that the primer adheres to the aluminum mast far better because I used the etching coat. It is highly toxic so you will want a good respirator when applying it. I didn't use it on the boom and chips in the paint go thru to the aluminum.
For prep, I removed all bolts and fittings that weren't riveted to the mast. I left the saddles for the spreaders, the gooseneck, and the vang attachement in place because they were secured with SS rivets and I didn't want to remove them. I see no downside to leaving them in place. I merely used a brush around those saddles and it was easily finished as nicely as if they had been removed. I didn't use a roller anywhere, I merely used a brush. With minimal care, I had no brushmarks, runs, drips or errors.
You will love the look of your boat when it is finished. Some people think that the gloss finish is too much glare and might recommend the product that flattens the glare. I disagree. The whiter and the glossier the mast and the boom is, the better. Glare is not an issue.
The trickiest part in my mind was not allowing too much paint to accumulate in the sail track but still get coverage inside. I would like to hear comments about how to address that issue.
Thought I'd post a picture ...