all shimano parts are stamped somewhere with a product code and a date code. The product code consists of the item code plus groupset, so all front derailleurs are FD, and this groupset is 6400, 6401, 6402, 6403. basically the 6 indicates it is in the 600 range, the 4 indicates the version of this range (with 6200 being the first, and modern 10 speed ultegra currently on 6700), the last two digits indicate the slight changes in the product, which don't constitute a whole new range.
on the front mech on the back there should be a stamp FD-.... If it is something like FD-6400 then it is tricolor model.
On the shifters, on the inside of one of the levers should be a stamp SL-.... Again if its is SL-6400 it will be 7 speed indexed tricolor.. If it is SL-6401 it is 8 speed indexed
it is probably worth having a look at the rear hub again as unless it is physically snapped in half a hub is often salvagable. you may need a new freehub body, bearings etc but its probably worth looking at
Also if the rear mech is 6500 it will be 9 speed, and compatible with 8 speed
Front mechs are pretty mech all the same so you don't really need to worry about that