Not ALL 6.0s need studded, I have 95,000 miles on mine, my 2 friends are well over 100,000 miles, all 3 have OEM head gaskets/bolts. There is no "if/then" for 6.0s, some push head gaskets like its cool, some don't. The "hose clamps" used on the EGR coolers are a joke, and if you can run without one, do it. But, you may need an SCT to turn off the CEL. A coolant filter/flush are good ideas, but unless your EOT/ECT are over 20* apart, leave that alone too.
Despite the issues, I'd rather have a 6.0 than my other friend's 7.3. I have better performance, better mpg, and with the right tune, there's NO reason why it can't pull like a 7.3.
The BIGGEST problem with buying a used vehicle is that you are buying someone else's problems. the lower the price, the higher the probability of it being a money pit.