first thing to do is buy you a repair manual for the tractor, perfer one that will tell you the operation of the tractor, plus fluids, maintenance items.
fine old tractors, but as with all tractors, they have some drawbacks and odd ways about them.
biggest drawback to D14 is going to be your lack of power clutch, AC clutch will work fine for AC equipment,
but my old AC D14 did not like to change direction (forward/reverse) with the bushhog pto running. this made changing directions a bit hairy.
just keep going forward and its not a problem.
good luck and be carful
((((((my old tractor D14 would start in gear, other makes had a ingear shutoff so they would not start in gear, this little item can be very dangerous))))))))!!!!!!!!!