That old Lindberg kit isn't actually too bad. It's certainly preferable to the other once-commonly-available one, which was originally made by Pyro and reissued under the LifeLike label. On that one, for some reason, the turret is off-center.
Apparently one common "paint" during the Civil War was a concoction containing tar, lamp black, and I'm not sure what else, which was effective at protecting iron from rust. It seems to have been applied ubiquitously to cannon barrels, iron parts of wagon wheels, and just about anything else that was made of iron. It did indeed have a shine to it, at least when it was new. I haven't done any research on the Monitor in a long time, but I rather suspect that's what the "black" paint on her may have been. The guys in charge of the Confederate ironclad Neuse, whose remains are about 25 miles from where I live, think that's how Confederate ironclads generally were painted.
Anti-fouling paint in one form or another actually dates back to at least the mid-nineteenth century, and the use of lead-based red paint as a primer is even older. There's an old story that the inboard works and deck furniture of warships from the seventeenth and eighteenth centuries was painted red to camoflage blood. Recent research has established that the red paint in question was simply a cheap, durable primer.
A good, relatively new place to study the Monitor is the website of the Mariners' Museum ( www.mariner.org ). As you probably know, that's where the ship's turret is being conserved (though it won't be ready to go on public display for quite a few years yet). There are some good, useful pictures on that site.
The Monitor is the sort of subject that looks ludicrously simple and boring at first glance, but the more you read about it the more interesting it gets. Good luck.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.