My honest opinion based on description: You paid an average price for an average car. Rust free GN that's all there and runs decent is worth $6k IMO. ALL the stuff they listed? Well it's 20+ years old and stuff needs fixing on a 20 year old car. Most of it sounds like it's not urgent and makes for good weekend projects. Most of those parts aren't expensive so as long as the car runs ok and steers/stops ok just drive it and work on it. Get some sort of anti theft or it will be gone next time it's in a parking lot unattended. When you get done with it you will have a car that you will know inside and out is done right and you won't have any more invested in it than any of us have in ours. Nice GN's aren't cheap. Basic supply and demand.
Other things: If the rear main is just seeping and not pouring oil out, DON'T mess with it. It's a poor design and most of them seep a little. Mine included. Also other leaks (like valve covers) can run down and make it seem worse than it is.
I have a set of factory service manuals and I don't think I've ever used them. Most any info you need can be found here under the search function.
Stock powermaster brake system has proven to be unreliable for most, unless meticulously maintained. Most swap to vacuum when the powermaster goes out due to the cost of replacement parts. Vacuum works just fine for me.
Get the stock tranny core if you can. They had a different calibration and are worth quite a bit of money, even if you have no plans to use it.
Just my opinions of course. We could all go on for hours about the ins and outs of these cars, the important thing is to read, read, and read some more.
+1
Take that list and put in it order. If it needs wires, plugs, a basic tune up, I'd do that first. You might not need a coil pack. I would guess that you bought a car that's been sitting a long time and has 140K at least on the OD
Rust free is the key. These cars are not the cheapest cars on the road. It will cost you money, if you don't have it, get out now. Otherwise you'll get hooked and then stop keeping track of the reciepts
Go here and read:
Turbo Regal Web Site
My car was missing stuff when I got it, everything you need can be bought here or through a couple of vendors. See what transmission is in the car now, I fought with a KCF transmission and all kinds of issues. I replaced it with with BRF and it's a whole new car.
Replace Ignition Coil pack - ?
Coil pack bracket missing bolt - NBD (No Big Deal)
Stock replacement turbo - rebuilt - Does it smoke? Figure $500 for an upgrade used.
Replace ECM prom chip - Have to, based on todays rotten gas
Replace IAC & gasket - Clean it first
Throttle body service - ???
Replace upper radiator hose - Visual inspection will tell you
Replace lower radiator hose - Visual inspection will tell you
Replace water pump - Does it leak? $35.00
Replace pass side oil breather and grommet - NBD
Replace both valve cover gaskets - NBD
Replace spark plugs and re route wires - NBD
Replace fuel filter - A must
Relocate ground wire from water pump to cylinder head - ??
Replace missing fuel line bracket bolt on timing cover - NBD
Air filter – K&N reusable includes mounting IAT sensor - NBD
Replace rear main seal - A little more difficult, they all leak a little
Oil pan gasket - tighten the bolts first to buy you some time
Oil
Oil filter - NBD
If you don't have tools or knowhow, pay for this stuff below:
Replace inner / outer tie rod ends with center sleeves
Inner tie rod end x 2 (moog)
Outer tie rod end x 2 (moog)
Center sleeve x 2 (moog)
Replace upper ball joints & upper control arm bushings
Upper ball joints (moog) x2
Upper control arm bushings x 2
Install 4 missing body bushings
You will have to have a Scanmaster to see how it's running (Have to have)
I'd replace the Fuel Pump and install a hotwire kit.
Mine spent it's first summer on jack stands so that I could go over everything to make sure it was all OK. If the Power Master break unit works now, I'd sell it and take the money and buy vacumm break set up with new flexable lines (I'd guess they are bad too).
Expect your $6K car to be $10K before you know it. But even with a decent paint job, your still under $15K
And they will always need somthing
My 2 cents
)
Id say dont be afraid and do the work your self. Save the money and learn about the car. These cars are really easy to work on compaired to many other newer cars. (Camaros and Firebirds come to mind lol) If dad dosent want to help get a good set of tools and start on your own. Tools you dont want to buy can be rented at Autozone and many other auto stores. 
