Or maybe just no one's had a chance to respond, things are usually slow near the weekends [edit - see? whiile I was typing, ascension replied too, hah!]

Making brushes from your own art is pretty simple, wether you ink them or not is up to you - I might suggest scanning them both before and after inking, then turn both into brushes to experiment, or deciding which one you want to keep. Once scanned, you can run them through sharpening or blurring filters, or adjust the contrast, so that's worth a go before you decide on what you want to keep.

As to creating the brush palette, it sounds like you're familiar with creating the brushes in the first place, so you seem like you're wanting to figure out how just set it up so the brushes you want are in their own file?

Assuming that's the case, it's pretty easy, the key is that you need to go to the Edit> Preset manager
Switch that to Brushes (i think that's the default anyhow) and you can manage your brushes from there.

The easiest way is to highlight the brushes you want to save as a set (select individual brushes by clicking on them, ctrl-click to add individual brushes to the selection, shift-click to add a range between the first clicked and the shift-clicked one) and then tell it Save Set.

Then you can store them or distribute as you see fit. You can also sort your brushes by rearranging - click and drag.

As to the map you uploaded, it's a good map. the only issue that jumps out at me is the style of trees is not consistent with the other symbols on the map. Other than that it looks great!