Ability to create custom status, already asked and voted many times, should be the solution to this need :-)

If will be introduced custom statuses as asked many times, surely also this need will be satisfied :-=)

Other similar tools like Collabtive has a dashboard per project and another one per user.
In first one, are listed all tickets of a specific project not depending by assignee, in second one, are listed all tickets assigned to current logged user, across every projects.

In my opinion both are useful.

Move or copy. Some test plans (i.e. Login procedure) is the same across projects. Copying it to different projects, could help

I think that instead of duplicating test plan, could be better to add a sort of version history to a specific one. In this way, number of test plans does not "explode" and everything related to a specific Test case, could be grouped.

I was thinking in something about this. I admit that I don't have clear ideas yes, but maybe right logic should be that when a Test case fail for some reason (or in a specific step) could be possible to open directly a specific and related Bug.

This was already asked here: Formatting of text in Bugs detail.
This was written for Bugs description but same logic could be applied to Test cases ones.

I'm available to do Italian translation, I already wrote to email address but did not receive any information yet

Slack.com allows integrations with Drive, it could be an ideal inspiration

I agree with a more powerful and strong integration between two worlds. Effectively, "steps to reproduce" in bug report, is almost overridable with test plans. Don't you think?