nnimap expiring/filtering & gmail->offlineimap->dovecot

[Dmitrijs Ledkovs]

Hello there,

I'm starting to use gnus, so far I've switched to gmane for all mailing
lists and slowly starting to read a few labels via
gmail->offlineimap->dovecot->nnimap which seems to be quite common.

I know have two questions about mail splitting and expiring.

1) If gnus splits mail via nnimap will it propagate back to gmail via
offlineimap?

2) How does expiring work with imap?

Right now I have double amount of mail on my computer because dovecot
stores one copy and another-one is fetched by gnus. If I expire articles
in my nnimap for dovecot, which mail will be deleted? (options: ~/Mail,
dovecot-maildir, gmail imap server) 

Is there a way to expire mail and fetch only partial amount of mail with
gnus? (without using nnimap live against gmail, since that's slow)

With regards,

Dmitrijs.