ICloud mail not staying in sync across devices

Question

I upgraded to iCloud on two Macs running Lion and one iPhone running iOS 5.  My mail (Apple Mail 5.2) no longer stays in sync - it used to work seamlessly via MobileMe.  I followed all of the instructions to migrate my mail accounts.  Here are the issues:
If I delete mail on the MBP, it does not delete on the phone...
After deleting messages they reappear within mail (as READ mail) on the MBP and on the iPhone
I cannot access my old sent mail (prior to iCloud move)...mail keeps trying to open but is never able
I checked all the mail settings on MBP and phone and they seem right, but I'm unclear about IMAP vs. "IMAP enabled" as referenced in another post.  I see that some folks are having mail sync issues, but I've not found any posts that specifically spell out the above issues.  I have not yet synced the phone with iTunes since the migration.  Will do that next.  Also have not yet tried deleting the account on the iPhone as I want to understand the IMAP issue first.  Another thing that I'm unsure about is why iCloud defaulted to my @mac address (vs @me).  I read an article that said I could change that, but I don't know if that's appropriate at this point.  Perhaps that is the underlying issue!!
Thanks in advance for any suggestions.

Answer 1

Update:  I spent an hour on the phone with AppleCare on Sunday and the problem is now resolved.  In case I'm not the only one out there with this issue, I will share the solution that worked in my case.  In a nutshell, I had to empty the trash folder in my iCloud account.  I have it set to autodelete every 30 days, but should probably do it more frequently.  What I noticed when talking with the advisor is that no mail had entered my trash can since the migration to iCloud.  Even though I knew that I couldn't permanently delete mail from the inbox, I hadn't noticed that it wasn't staying in the trash.  In fact, it wouldn't go to the trash at all.  I would hit delete, and it would go into space....then reappear in the inbox a minute later.
We tried a number of things before the advisor had the idea of clearing out the trash can.  We first verified that I was able to delete email while logged into icloud.com.  Then we set up a new user and linked the Mail app to my iCloud account, and the same issue presented...except in this case, there was no trash can even present because it was a new account and I could not delete any trash.  We tried removing the iCloud association and then setting it back up - no change.  Of note is that my Gmail account continued to work fine in terms of deleting mail.  The problem was specifically with the iCloud trashcan.  Once it was cleared out, I was able to delete a weeks worth of email. 
For what it's worth, I am still unable to look at my MobileMe sent mail, which I occasionally like to do.  A new new folders were created during the iCloud migration:  MobileMe Sent mail, recovered mail, deleted, and junk.  These folders appear to be empty now, but earlier in the week I could view the message headers, though the messages would not load.  Now I don't have access to them at all.  So a word of caution to anyone that really needs copies of their sent mail on MobileMe....you may need to copy that mail to a new folder before migrating!