1) Diversion to Frankfurt isn't that surprising if the flight was from Berlin - not necessarily an LHR Wx issue.
2) Most shorthaul flights would have been held on the ground in Europe with a nightmare slot as opposed to going around in circles in the LHR area. This sort of fun and frolics reduces the flow rate to 38/60 so you know as soon as you arrive somewhere that it may be a while before you get back. Good job it's the weekend and less flights.
3) The 3 0715 BOS flights are all the Virgin flight but with codeshares.