Thanks, I've fixed this in 2.10.2.

You could select all vertices and then deselect all vertex groups in turn. You'll be left with the unweighted vertex.

What version of the source tools and Blender are you using?

https://developer.valvesoftware.com/wiki/Blender_Source_Tools_Help#Meshes

Yes. Move it away from the pink area.

This is due to the filtering applied to the texture when it's scaled up. It's effectively a blur effect, which means that colours from nearby pixels will bleed over. This is something that the GPU does and is not a bug.

You need to add a margin between your UV islands, or disable filtering in your VTF file.

Corrupted UVs was a bug in 2.10 which I just fixed. You've not told us what the problem is so I can't help any further.

Oh dear. I did test this but I must have only looked at DMX imports. Fixed in 2.10.1.

2.10 is out and this problem is not part of it. :)

I've found a much better fix for this and shipped it in 2.10.