Google Tasks – Move from Gmail to Google Apps Account

Actually, marking a task as complete doesn't delete it, even after you choose "clear completed tasks". You can always view completed tasks. In the console view ( https://mail.google.com/tasks/a/yourdomain.com/canvas ) just choose the "Completed tasks" view. In Gmail or Gcal, you can choose "Actions/View Completed Tasks".

You can always export your Contacts to a Google CSV file and import that file to your new Contacts. Just hit Gmail in the upper left corner and select Contacts and find the Export option.

I see that the normal Gmail Import functionality is not available for Apps. You can always add your old Gmail as a POP address and import the mail that way. Here you can enable POP in your old inbox. And here you find the configuration you have to enter in your Apps account.