As for getting the back off Will, next time get yourself a 17mm nut, stick it to the back with superglue and leave for 10 mins, place in a decent watch holder or vice with wooden blocks, undo with 17mm socket, drop the caseback with attached nut into acetone which will separate it.
Sounds drastic but it works & doesn't mark the back, additionally its the only time I have ever found superglue to work properly!