Has anyone tested or have good anecdotal evidence of whether attacking at long range (Regular or Magic) would improve skills faster than thrown range because it's harder to hit/damage? I read a topic here that suggested spell damage effectiveness decreased with greater range so I wonder if that is compensated for or whether I should let monsters get a little closer before blasting them.

I think successful hits increases your chance to increase the skill levels as well as repetition but I can't say for sure. If Scatter was around he would be able to give us a good answer to that.