the watch dial meter is 46.6mm
it is not using 7750, but a modified movement derived from seiko 6s37 which I think you hardly find this in other European watches.
in terms of accuracy, i am not the owner of the watch but i believe that it is up to GS standard.
to clear ur doubt jos2012, yes, it is a column wheel integrated chronograph movement.
u can see the column wheel from the picture which is on the left side of the eight pointed star junghans logo