dovecot - Jun 2011 - virtual users with postfix+dovecot plugin usage question

I'm interested in if i should enable plugins only in LDA as i
understood that with postfix dovecot works only like LDA.
For example i wanna use autocreate plugin for imap user i have enabled
in both IMAP and LDA sections. Is it right or i had to configure it
only in LDA section ?
Than how quota and imap_quota work in imap section ? For what is it
there if lda controls user maildirs ?

Dovecot 2.0.13

protocol lda {
  mail_plugins = quota autocreate
}
protocol imap {
  imap_client_workarounds = delay-newmail
  mail_plugins = quota imap_quota autocreate
}
protocol pop3 {
  mail_plugins = quota
  pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
}