Thank you everyone for the replies! After much deliberation, I decided that the critique about my work is well worth posting it on a public site.

And ProfGremlin: First, I'm glad the thread has proved useful to you. I'm going to bookmark it myself, as there is a lot of information there. I can't help but be nervous though, as I have put a lot of time into this map. Also, to your questions.

1. I currently don't have any computer programs (other than iPhoto and Paintbrush) that can allow me to edit the picture. I have done a little bit with Gimp before, is it a free download? If so, I'd love to get back into it, and maybe do some different things with my map that way. However, for the things I'm working on now (political map), the gridlines are very useful. I like knowing the distances between various places, and therefore have a general idea of how long it would take to get from one place to another.
2. Yes! It's a volcanic island. The volcano itself is most likely dormant, although I haven't quite decided yet. The ensuing chaos and happenings after the eruption would make for an interesting story though, wouldn't it?