2nd question: Are you being distracted by the awesome paint job? I admit I often have this problem, but you might want to make sure it will match your riding needs and budget.
I'd say if you can afford the 800, give it a test ride, and perhaps see if the owner will budge on price. If it seems like something you'll love riding, go for it. Just make sure you get a solid lock or two, it's pretty flashy.
Yes - does fit, and yes, definitely distracted by the paintjob a bit. But still, it's within my budget.
Would 400 for the frame/fork/hs/bb/panto stem/seatpost/pinarello saddle be reasonable? I want to say yes, but I'm not too familiar with prices on vintage road frames.
No, that's a lot of money for a bike that isn't ready to be ridden away on. Nothing incredibly special about it. But if you have a spare wheelset or access to the rest of what you'd need on the cheap, maybe go for it?