I've been working on the plate tectonics for my world (Tamanak) recently, and this is what I have so far.

Current time (1 mya, due to some gplates quirks)
Blue: subduction, arrows pointing to upper plate
Red: spreading center
Green: transform boundary
Tamanak 1 mya.png

50 mya-1 mya: https://www.youtube.com/playlist?lis...4OGwY0rooL-q22

First off, this is still very much a work in progress--I should probably revise the upper left corner of Phaena, for example. I also haven't drawn in the island arcs at subduction zones yet. Regardless, do these tectonic maps look plausible? Is there anything I should change?

I also have a few questions about plate tectonics in general. In no particular order:
I think I have a decent idea of when subduction zones disappear (it seems to require serious continental collision), but how do subduction zones arise?
What happens when continental crust reaches a subduction zone and there's no continental crust on the other side to stop it?
How does continental crust form?

Thanks so much!