A regular paper joins the publication queue and will be scheduled to an issue as space become available, and this can be up to 12 months after submission of camera ready manuscript. You will be contacted by IEEE with a galley proof of your article about 6 weeks before the cover date and you have 5 days to respond.A paper accepted for a special issue has a known publication date, but the final manuscript must be submitted by the date advised by the editor-in-chief. Failing to meet this deadline means your paper will miss the special issue and go to the end of the regular paper queue.
You can post a copy of your submitted paper (not the final formatted version) on your own web server as discussed below.
Papers are now rapid posted prior to appearance in the print/digital issue. These papers are on IEEE Xplore, have a DOI and can be found by Xplore or Google search. They don't have a volume/issue/page number but are otherwise fully citable. You can find such papers via the "Early Access" button on the Magazine's Xplore page.