Hi there,
As far as I remember, the permissions from Exchange side (mailbox permissions) are synchronized to the EV archives, so, if the user has the rights on the mailboxes, it will also have rights on the archives.
As for accessing the archived items, you could set an Outlook profile for a speciffic mailbox and then you can open the archived items. Another way is to use the Archive Explorer and search there (all the archives where the user has access will be listed.
Please let me know if you would need more help on this.
Hope this helps.
Olivian