Don't do yourself down - those mountains are actually pretty good. Good work so far. I'd certainly invest in a tablet at this stage (I know you know) but that must have taken forever with a mouse - and most of the 3D mountain stuff really needs something pressure sensitive.

Anyway, for this many mountains I would suggest getting hold of a nice mountain brush (there must be one floating around) and using that to block in your mountains.

As for the forest, well it depends on the style you are going for. At this scale, this forest is most likely going to look like a rough texture without any resolution for the trees itself. I'd go for a dark green and try to find a rough texture (or a generated noise pattern) that works for you.

So far, a great effort - both in achievement and the scope of the project! Definitely keep posting progress shots (though perhaps slightly smaller files than those - wow they were a bit enormous. Odds are you can drop the jpg quality settings to get the file size way down below the multiple MB you have here without compromising your quality too badly).

And of course, a little rep to get you started.