1. I have the same problem (med + 127 is too low). The mic gain and the recording level do the same thing; the gain is for broad changes in input volume and the recording level is for fine-tuning. (I know this because I just looked it up a couple of weeks ago.) Another reader who was also having this problem sent a few tests for me to check. It turned out that med + 127 yields the same volume as high + 100. So I recommend that you try setting your gain to high, recording level to 114, and see how that works. When I tried it, the volume was still a little bit low at that level, but see how it is for you. If you don't have the Mp3 Gain software already downloaded to test your volume, just post a sample here (or PM it to me) and I'll be happy to run it through for you.
2. Mono vs stereo recording. My
H2 doesn't have that option (I think it's a new feature) but if I had it, I'd use it. I have to convert the stereo files to mono in Audacity. Just make sure your mono ones are playing in both ears. I think the new
H2's can also record in mp3, which is cool, especially if you have limited hard drive space for the wav's. I don't think the quality loss from one mp3-to-mp3 conversion is audible, so editing an mp3 file and then exporting as a new mp3 should be fine. You might want to record in wav for files that'll be edited more than once, though (i.e. for dramatic works).
3. Multiple files. I do the same as Esther, I just keep the
H2 going when I have to take a little break, unless it's for more than a couple of minutes. I also changed to a larger SD card, and, like you, I didn't realize that changing the card would reset everything until after I had recorded a really long chapter (which came out barely audible). Bah.
4. Figuring out which file is which. I think there is a way to rename them on the
H2, but I've never tried (I never have more than 2 or 3 files on it, usually false starts or something, so it's easy to remember what is what or to just get rid of the ones that are only 2 seconds long). I usually upload my recordings right after I make them. Then I just listen on the computer if I can't remember where I stopped.
5. No help on the closets, though I was in a large home-goods store today (no spam, right? It's the one from Sweden

) where they had some lovely sliding doors to cover up hanging clothes, and I wondered if it would be weird to install those in an actual closet, as opposed to out in the bedroom as they had displayed. ha.