Thanks for the input. I do have a Dremel, and have used it to clean a bit of the big stuff up so far. I used some 180 grit sandpaper to sand down the major lines and bumps. It left behind almost a very fine sponge-like look, with dust filling the holes in. It feels smooth though, and I expect the primer will seal it all in there smooth (I hope).
This is just a practice bucket that I'm going to do a custom paint job on for fun, so I'm not bothering with the upgrades. I'm having a proper helmet made and painted for me that will have all that stuff 