1. This is a limit enforced by studiomdl which isn't present for SMD. There's no getting around it.

2. The exported DMX isn't triangulated (check by importing it), but studiomdl will do that. Perhaps you have some tris hiding in your model? Seems a bit weird that the mesh has to be 100% quad BTW...

The shape normals thing may be a bug with the engine. If you can reproduce it with a single shape active let me know, otherwise it's probably not my problem. :)

This is caused by not having the VPROJECT environment variable set. It'll be fixed in the next release.

OK, I'm now able to use this new method. I'll look into this shortly.

As Foma says, you should provide the path of a QC file. You must create the QC file(s) yourself.

You can use wildcards to match mulitple QC files if you need to.

Yes. Mesh-compatible objects are exported to their own files unless you group them together.

Sounds like a Blender problem. Try asking for help on the official website.

They must have increased the limit for SFM. I'll look into it. If you can work out the new maximum that would be great...

They are created as Actions. That's all. There is no way to link aninmations to objects, much to Blender's detriment.

No idea, it's probably something done by the FBX exporter. Or perhaps you already imported the animations at a different time and Unreal is linking them up automatically?

When importing the weapon you need to uncheck the "append to existing model" option. Then go into pose mode and add a Copy Transforms constraint to the weapon bone, targetting the character bone with the same name.