This is a glorified cylinder, but I'm getting lines as you can see from where the smoothness of the hi-poly is being translated onto the low poly. Is this just because I don't have enough loops on there or something else?

Also, the other thing that is bugging me is that I have floating panels on this thing, but the normal map just makes the curvature a little screwy (the top is fine, though). There are a couple of other things as well, as you can see, but not as glaring.

could you post the normal map too? most probably a smoothing group issue....

Those strange lines:

Looks like you've got a UV overlay image on top of your normal map.

The wobbly edges:

Might be you need to tweak your projection cage so it "sees" the side of your cylinder straight on, or use the ray cast method of baking normals.

EDIT:

Thanks you, guys. Figured out the problem was a combo of smoothing groups and the cage not behaving.