You can get very workable inexpensive tablets that are just fine for this kind of work. Just go to Amazon and search on "drawing tablet" in computers, and you will find plenty of choices around $50-100. Once you have made your 5th post so you can send private messages, feel free to PM me and I'll give you what info I have on brand choices.
What you suggest for problem 2 should work fine. I draw a general shape at the high level, then make a second layer to zoom in and redraw it in finer detail. I do the same thing for regions such as mountain ranges or forests ... outline the area in a simple grey or green, then zoom in and do the actual mountains or forests on a new layer on top of that. Then erase your planning layers and you have it