I'll try to answer them as I wrote the software..
1 - There is no good list of messages supported - sorry! I'll see if I can improve that.
2 - The version number you set is that in MSEX / SInf, nothing more.
3 - You might have found a bug there.
4 - Here as well, there is no particular requirements for how to go down apart from closing the sockets nicely with close(), but that's ordinary netiquette.
5 - The browser does not support thumbnails. It might in the future.
6 - I had to go into the code to check and it does. However I don't think I've released it yet. I'm going to look into releasing a new version, maybe even with the source code. It might even contain fixes for 3 and 4.