V-Flyer

Are ALL unreserved seats except for exit/bulkhead, available for DIY check-in unlike pre-assignment? Also, are even exit/bulkhead available or do they have to be allocated in person at the check-in desk?

I don't know about all unreserved seats, by exit row seats are not available via DIY check-in per VS website:

http://www.virgin-atlantic.com/en/gb/faq/preassignedseating.jsp