I too am a new owner of a 968 (cab) and yet I already recognize many of the items you list as being common wear and repair items. Some are fairly expensive such as dealing with the oil leaks/new seals and motor mounts. The tab for these alone will likely be more than $2K. There are a lot of seals on the front of the engine in addition to the rear main, oil pan, and valve cover. Motor mounts are a couple hundred dollars each and about 4-5 book hours labor to replace.
I’m not sure if the “major service” they’re referring to means timing and balance shaft belts, but if needed (likely) add another $2K including the (while you’re in there) water pump.

The A/C should be R134 from the factory on this car. Unknown whether a recharge will suffice or whether you need hoses, fittings, compressor, etc.

The power steering reservoir hose may be corrected by tightening the hose clamp, but I’ve just elected to replace the reservoir and hose on my car for about $180 all in.

You might find the radio code written somewhere on the car or in the owners manual, etc. IIRC it will be a four or five digit number.

I just purchased new hood struts through Pelican Parts, but most online Porsche parts places should have them. They were something like $25/ea for the OEM items I chose.

Door seals, if a new one is needed, should be available through most parts houses too. I wouldn’t be surprised to see that part be $100-$200, though it might just need to be reglued.

You might search the forum for discussions about all of these issues. That’s how I’ve learned quite a bit about them.

Oh, and congratulations on the car!