a useful tool for your comments statistics is this Addon:
Of course you should visit the blogs of your "top commenters" regularily, this is sort of politeness.
The other point: reduce your huge list of photoblogs to those in which you are really interested and combine that with the blogs of people who give honest critique (and a lot of course ;-))
To gain visitors, the weekly photomemes are a good point to start with, although this leads rarely to comments. It is great fun anyway :-)