View filter (and search) by tags?

Hello. I need something:
1. I want moderators be able to create new tags (local for my forum).
2. I want tag could be typed (and checked if it exist) during creation of post and especially post replay.
3. I wand a user could select post and post replay view option (show on list top/bottom show or don't show it in the list), by selecting tags (for example from a tag list).

Because I'd like my forum to be multilingual: I want one topic with many replays (in different languages); and want readers could show/hide answers on some language.
Also I want cross-post tags; i.e. I want users be able to see list of topics or/and replays containing some (mixed) tags, for example "category:game" and/or "tested_ok".
Would it be useful? Can you recommend me something?

upd: slg, it depends is there such an option or not; ok, let me try to make a poll...

Is this a suggestion or a support question? If it is a suggestion, please add a poll.

I've got a suggestion to use http://vanillaforums.org/ , but it supports view filter only by one tag; for more than one tag filter there need additional programming.