2004 Passat 1.9L 130PS Diesel ~100Miles 5-Speed Manual SITTING, HELP FOR REPAIRS

Hi, I'm new to this forum and a new driver all together (at least in the car world, not really on the motorcycle world) so I don't really know how to act or what to expect. My problem is quite clear, I have a 2004 Passat with around 100 miles running a 1.9L 130PS diesel engine, the car never had or needed any substantial repairs at all. However, this car has been sitting in my garage for the last 4 years, in the first couple, I would start it every 6 months or so and let it idle for about 5 minutes but I lost the habit after that. I also moved a couple of times just a couple feet (engine off) being the last time just yesterday and wheels spin freely, no problems (e-brake was off during the 4 years so the breaks wouldn't seize). My problem now is that I need the car, I will need it up and running in about a month or so and because of that I know I got to work on it. My questions begin: What MUST I do before starting the engine? What SHOULD I do before starting the engine? What MUST I replace before calling it road ready? What SHOULD I do before calling it road ready? I there any parts I could replace just to be sure? How much should I spend on it? Is it worth for a car that old? Do you think it still got some good miles on it? Now some facts that might be of some importance: Car ran fine before being stored, it was used almost daily if not daily and every light, switch, door, button, everything just worked; Battery was connected and is now dead, obviously. I got a replacement, not yet installed; No rust visible apart from a 0.5 inch spot on the roof which will be taken care; Interior is beautiful, dusty, but absolutely untouched, looks new; Car was almost every time stored in a garage during it's lifetime; Quite a few miles as I said before; Tires look OK, I filled them every 6 months so they didn't become brittle; Old diesel on the tank; Every fluid in the car is old; Some water got condensed into one of the blinkers; It's a 5 speed manual, original clutch (I THINK, IF THIS IS HIGHLY UNLIKELY, MAYBE IT ISN'T!) Maybe no so important facts: I live in Europe; Here diesel is quite high quality; It was running nice oil; Mostly driven on motorways and secondary roads, rarely on city's;