First, it looks very bumpy. My suggestion (take it or leave it) would be to take out a big eraser (100 or 300 pixel airbrush tip) and turn the flow down to 5-10% then erase some of those bumps. With the low flow you can go over an area many many times before it is completely gone so the eraser works kind of like sculpting. If you want more refined valleys then use a smaller tip.
For the borders, I assume you're referring to national borders. Grab the pencil tool, use a 2-pixel hard square tip, draw a shape and make sure that the ends meet. Grab the paint bucket tool and fill the shape. Ctrl-click on the "base" layer, select - inverse, then hit delete on the keyboard and deselect. This makes the shape fit the coastline without altering anything inland. Set the fill of the layer to 0, add a layer style of stroke and inner glow of whatever colors you want. When doing the other nations you will also have to delete the parts that overlap inland. For that you ctrl-click on one nation, select - inverse, delete and deselect. If you have 20 nations that process can take a while.
On the plus side, looks pretty good so far