p8pbb bridge doesn't have own database tables, so the its own impact is minimum. But note that actually both phpBB and Joomla are loaded at once. Russian language is possible for contacting our Support Center, there is no russian language pack. Discounts are available ...

Yes, it is possible, slave site's database will be cloned to new site.
Note that MightySites doesn't work with folders like localtradeclub.co.uk/deal

Even if it's optional in the module configuration, with a note concerning this potential perf impact ? I'm a bit surprised, as i was running such functionalities with another module on another CMS, and there were no impact on the performance (i must say ...

... effect seo rating: No loss or lower seo rating what so ever. If anything, I almost believe it increased ours even without a current site map. ( Note: if you used a phpbb3 sef url mod, it will cause some issues- uninstall that first. I have tested it out just for the heck of it, and it is not ...

1. No files are modified in either phpBB or Joomla!. Only few lines of code are inserted in .htaccess.

2. Really works!!! Strange, but we should have the reason to note that, will perform more tests.