Mail Import Defaults

I have to use the import mail using the File -> Import -> Email … option to import email. Can the import button on the toolbar be made similar to the export button and offer a series of choices.

Further I use multiple mail accounts and would like to be able to store default settings for each account when importing. Is it, or will it be, possible to do this? I would really like to be able to set a series of defaults with the hierarchy flattened.