1. This L/C/R thing makes no sense to me at all. I almost never hard pan anything, even reverb returns, and when I do it's for effect. The only things that go in the center for me are the main vox and the kick, snare & bass. On good systems, you can hear tiny bits of panning, and it's pleasing as hell. There may be no wrong way to mix, but if there is, I have no doubt that exclusive hard or center panning is the wrong way (unless you track everything knowing you're going to pan like that, and narrow the field with mic placement). This is another one of those magic internet things, like 4-mic drum mic'ing; I've never seen a real-life engineer mix L/C/R, but it seems popular on the forums.
2. I agree about the lo-fi masking thing, and some of the sounds (drums & vox especially) are suffering for it. All the same, the mixes sound pretty good. Given your caveats, I don't know how much better you'll do without help and a lot of time. So, yeah, be proud.
