Couple of 300D questions

[engatwork]

I recently purchased a 1985 300D - turbo and have started working on it to get it set up to drive back and forth to work. My questions are as follows:
a) I am planning on "rolling on" a new timing chain and was wondering if the oil pump chain should be replaced at the same time. Mileage on the car is 215k. Has anyone on here ever seen the oil pump chain break? Can this be done without removing the engine?
b) There is a small solenoid valve (electric/vacuum) mounted on the firewall right behind the brake master cylinder. When I was nosing around under the hood I found the electrical connection unhooked. I hooked it back up but have not driven the car to see if it makes any difference. Can anyone tell me what this is?
thanks,
Jim
'95 E320
'97 CRV
'85 300D