Turns out, the vB3 version of DBSEO was lacking the plugin that made this work. I've added it to your site and I can confirm old links are redirecting now. If you experience any more 404 errors, please change the URL format back to what it was and re-save, then change it to your desired format and save again.
The & is trasformed in "and". I know there is an option to change that. I need it to be tranformed in "e" (Italian), but I don't remember where is that option in the SEO CP. Can you please help me?
The reason for the extra dash is the exclamation mark at the end of the forum name. You could try adding it to the Custom Character Filter and see if that works
There's no option to remove or replace the "and" at this time, it's hard-coded. I'll look into that for a future version.