Hi,
1. Thank you for your report, we've just released an updated version of our VM extension that should fix this problem.
2. You can enable Menu Associations in JoomSEF's Configuration on the Language tab.
3. The first part of SEF URL is usually a menu item name. This should be handled correctly for different languages if you have menu items correctly set up. Unless you have it configured as a Custom Menu Title, which currently doesn't support multi-language handling.
4. Breadcrumbs are handled entirely by Joomla and they're generated according to the selected menu item for the SEF URL, which is controlled by the Itemid value stored with the URL. Use JoomSEF's URLs Manager and check that the Itemid value stored with your URL corresponds to the correct menu item ID that you can find in Joomla's Menu Manager.
5. It is not currently possible to have different extensions parameters for different languages. We're planning this feature in some future version, but I can't promise any ETA.