Hi Andy
The boat shown is my Parker 325, "Sulito".  I installed a Lewmar 1000 windless a few years ago and it works very well
1/  Electrics:   I replace the electric to the hydraulic ram via a isolator switch.  From this isolator switch there are two leads, one to the hydraulic ram via a 120 amp breaker, the second to the windlass via a 70 amp breaker. This is on the wall of the locker in the forecabin  that housed the Hydraulic pump.   This means that when we are living on the boat I can turn both these powerful electrical units off.  From the 70 amp breaker a lead is taken to the chain locker and the solonoid for the windless is housed on the rear wall here.
2/  The hole, 3" for the chain drop into the locker is back as far as I could move the unit and a small section of PVC pipe resined in.
The chain drops in at the rear of the locker. I did glue hard plastic board on the rear wall and floor of the locker underneath the chain drop as to not damage the locker itselk.  
3/   As the locker is shallow, when retrieving the chain you may have to move the chain forwear to stop it building up in the one spot
4/  The front two bolt holes for the windlass are in the chain locker and the reear two bolt holes are in the roof of the forward cabin ( covered by the lining).[attach]1202
I will send photos when I can work out how to download them
Regards
Barry