If you have a front mounted chipper without any weight on the back the biggest you could go is about 6 inch (note that you wont have chip in the back all the time), due to the mog already haveing a large nose weight for heavy loads on the back.
ACPrice engineering in ingleton actually does an adaptor for ducker would chippers so you can change it from linkage mounted to din mounted.
The only real advantage of front mount is you can then tip the body all 3 ways.
Front mount implements are usually removed by wind up legs, or they can be hydraulic.
Schmidt and din plates are different things,
schmidt plate

Used mostly for ploughs, although these days ploughs tend to use din plates. also doesnt always have the "toplink" bit.
Din plate

Often called a schmidt plate, its actual name is a din plate. can be folded up when not in use for off road clearance.
The din plate will give you much more flexibility as not much equipment uses schmidt plate these days.
Casto you shouldnt need a tool box to counterbalance, with the weight of the engine, but i know you want it for chain saws and stuff as well

Like casto says, your gearbox will last a lot longer if you can double clutch, only when moving down the gears though.
Regarding the pipe over the cab, it goes right into the back body, but can be awkward to put on the chipper. (having to climb up to fit it)
