James, since you're living in Canada, I recommend that you add Canadian Musician to your reading list.

This mag covers all aspects of the music industry in Canada, with columns written specifically for players of many kinds of instruments. Its a very good source of information on the business and technical aspects of making music.

You'd be surprised how much of the material intended for other players has relevance for guitar players. An article for bass players on 'building the groove' can be a big help to a rhythm player, for instance.

Check it out.