Masstagging genres

[so_la_la]

I consider masstagging genres using the last.fm genre tool.
Is there a possibility to keep old genres? (To be safe I have made playlists with my old genres.)
Is there a possibility to delete unwanted genres from the genre tag even if it features several genres?
Can I search and replace genres so that I can e.g. replace indie with independent or post-punk with post punk etc? Can I streamline the keywords tag in this way too?
Thanks.

[so_la_la]

Can I search and replace genres so that I can e.g. replace indie with independent or post-punk with post punk etc? Can I streamline the keywords tag in this way too?

Ok, obviously i can do that through the additional tagging tools.

One thing i have noticed is that genres have been deleted from tags when there weren't any genres available on last.fm (MB is unable to find recommended genre for these files).
 I still don't know though whether it's better to tag first and then having to sort it or if it is better to define a list beforehand.

EDIT: And I can't seem to add a genre?