Welcome.
FIRST, replace all the fuses in the box. Yes, even if they appear fine. Also clean the contacts while in there. Many issues arise from corroded contacts. Also check the 10A fuse in the Over Volt Protection relay, this is by the master cylinder and is a rectangular box.
Radio could have a popped fuse behind it. Antenna only works when the radio is on. Are there dashes on the screen such as "- - - -" or is the screen simply blank? Blank is good, dashed out is bad.
There is no tachometer amplifier for the 603 Diesel. So the cigarette butt will not work. From memory the tach runs off the EGR controller down in the passenger footwell area. I forget where the pick up for it is at.
These clocks fail often. How to repair is beyond me. Probably something simple.
Purchase a MityVac and set the transmission vacuum properly. My guess the shift pressure was turned down to soften the shifts. This tool is invaluable in PROPERLY repairing one of these vehicles.
Pull glow plugs and test them properly. If they glow, they are good. If they do not glow, they are bad. This is the definitive test for them as simply Ohming them out will not always work. Chances are you have an out plug or so. Does your squiggly line light up when you glow the plugs? If not, you have one or more plugs burned out.
How long is the block heater pluged in for? And you should once again, Ohm out the cable and verify there are no shorts in the cable.
Sunroof is probably stuck, typical. Leave it shut until you are ready to deal with it properly.
Now, get to work on your problems.
