I've been working on the addressbook sync, but I'm stuck because I don't want to create a security issue. I need to revisit a couple things, and then I'll post back.
I have no idea how Trash would be synched. On VFEmail, everything is done via IMAP. Trash is merely another folder. The web interface is just another IMAP client. It's configured by default to 'move to Trash', when an email is deleted. (My personal preference is to mark as deleted, and hide the deleted emails, but that's just me). Your Blackberry would need to be configured similarly.
Now, I know Outlook has had issues with Trash and Sent-Mail folders on IMAP servers. It's possible Blackberry is in the same boat. They've done something custom, and you can't undo it. Unfortunately I'm not familiar enough with Blackberry to tell you for sure.
How are you using email in Blackberry? Last I saw, you had to configure a blackberry account to retrieve from a IMAP Server, but it's not actually IMAP. It's a POP-type retrieval, and does not really sync. If so, You would need a real IMAP client. I think this: http://www.imobilemail.com/
is what I gave another user a few years ago.