Thanks! 
Yeah there are 2 types of tectonic plate boundary, divergent(Think Atlantic Ocean), and Convergent. There are 4 types of Convergent Boundary; Andes, Rockies, Himalayas, and Island Chain(think of the area from Japan to Australia).
Erosion is a bit too long of a process for the physical and time scales of the game. Players will be able to level hills and mountains at some point though(Industrial/Modern era), and maybe even build them(post Modern Era).
For visualization of the sea floor, the current plans are to make the ocean out of 1 giant water plane, make it somewhat transparent, and then place seafloor tiles under that plane. Brighter coastal tiles, darker mid-ocean seafloor tiles, maybe some underwater volcanoes, vents, ridges, etc. I plan to make sea floor colonization a super late game ability.
The only time I will probably simulate weather patterns visually will be for hurricanes and other game affecting weather disasters, and maybe when you zoom out for a full planet view I could bring the clouds into view.
What kind of project do you have in mind? Always interested in seeing more turn based projects and any project with lots of procedural action.
I don’t know anything about the particle system, but it would make sense that you could.