[Dovecot] Sent mail issue

Dear All, I have few question regarding dovecot configuration for specific need which are as follows:-

1. I have IMAP folder with the name Sent Mail and i want whenever client uses any MUA to send mail from my server his mail must be kept in server's IMAP folder which is Sent Mail instead of local Sent folder.

2. Whenever user configures account in MUA, MUA automatically create some new folder like Junk Mail etc. while i am already using Spam folder to keep spam message in that folder so let me know how can i save myself from this.

3. Is there any thing which can also put deleted message in my server's Trash folder.

Thanks