This is intentional. Units in SMD and DMX do not relate to any real-world measurement. Both the importer and exporter write whatever values they find in the scene at 1:1.

This is intentional in Blender 3.1.0 only. You can downgrade or wait for 3.1.1 to get the browse buttons back.

3.2.1 has now been properly released.

This is a bug in the preview version that I have since fixed. You can download the latest build from GitHub, and copy it into your Blender addons folder.

https://github.com/Artfunkel/BlenderSourceTools

This is due to a GUI error which was fixed in the preview that you said you downloaded in the other thread.

I've reproduced the crash and filed a bug about it. You can avoid the problem by deselecting the "Relative Path" option in the file dialog. It's hidden behind the gear icon in the top right.

Please try this preview release:

http://steamreview.org/BlenderSourceTools/release/blender_source_tools_3.2.1_preview.zip

Please try this preview release:

http://steamreview.org/BlenderSourceTools/release/blender_source_tools_3.2.1_preview.zip

I can't replicate this in a new 3.1 scene. Can you check for any errors in the console window and/or upload your blend file, please?

This looks like a Source Filmmaker project. You can't import those.