Hi CDN, it looks pretty good. For D & H my gut says the plates are slipping, like the San Andreas fault in California. You might try and look at just the interactions between the plates, as in the style of "A Magical Society: Guide to Mapping" and see what types of mountains are formed by subduction, suturing, slipping, rifting etc. This may then give you confirmation on your choice of plate direction.

The Earth is roughly 70% water. Two ways that you can check yourself by comparing to Earth are to 1. load your image as an overlay in Google Earth and leave the borders on, 2. load it into G projector and put the Earth outline overlay on. I did the 2nd one and verified it with Google Earth. This also helps with looking at your land masses in a spherical projection so you don't get pointy artifacts at the poles.

Good Luck.