The plugin is at the point where some design choices early on make it hard to change things without breaking stuff. Plus the event system's speed and limits make it hard to allow the amount of flexibility I'd like without being overly verbose and complex. Anyways, that's partially personal opinion. Construct makes some complex stuff simple and some simple things overly complex.
As for your wishlist:
*The view distance is just an artifact of how the fog is implemented. There are pros and cons of either. Rewriting the plugin to have alternative options for everything would be an option i suppose.
*As I recall I try to fit the shadow frustum to just fit around the view frustum for maximum shadow detail. It's not perfect because some things off camera aren't being included due to some approximations on my part. There are alternate ways to do it, such as fitting the shadow frustum over the whole scene, but the tradeoff is giant scenes would have low res shadows. But I agree more work would need to be needed with shadows but it turned into just fiddling with settings to see what works well which was too time consuming.
*blend modes would be nice.
*opacity is already doable. You just have to turn on "transparent yes" in the object settings. The caveat is it's done per object. So it just draws objects back to front. Per polygon would be better, but more complex to do with how the renderer is implemented, also it still would have cases where the sorting would be off. Best would be an algo called "depth peeling" but it's slower.
*normals are already in the plugin. As long as an obj file has normals in it you'll have normals, which is used for smooth shading. If you mean normal textures, then no, only one diffuse texture is used.
*Collisions and raycasts are highly requested things. I have a good idea how to do them but I don't find I enjoy finding a way to make it usable in the limits of construct's event system.
Overall, I may work on this more, but I'm more inclined to work on other things first if I find the time and motivation to code.