Thank you Turambar, johnvanvliet, and MrBragg for the feedback.

1) To create this map, I used Gplates to define the tectonic plates and develop the tectonic history of the world. When I reached a satisfying configuration of continents, I imported the map into Photoshop, where I drew the topography and coastlines. The river networks were all generated in Wilbur but I'll probably end up deleting some rivers that fall into desert zones or rainshadows. I also used GProjector to rotate the coordinate frame in order to work on the polar continents.

2) I'm not sure which height map I'm using. I did, however, use a posterize adjustment layer over the original greyscale altitude map, so I'm wondering if this is what you're referring to. I chose 10 levels from the dropdown menu at first, then changed it to 20 later. Also, I've stroked the contour lines resulting from the adjustment layer, slightly.

3) Thanks MrBragg; I'm planning to clarify the subduction zones in a future update, but for now, convergent boundaries are purple, divergent centres red, and transform boundaries, green. I'll also submit the tectonic history video in a future update.

Again, thanks for your interest.

Peter