There's been a bit on this - if you search the board here you'll find some comments on the topic.
Ill answer your questions the best I can... (I could be wrong as usual!)
" Are car alternators designed to run at full output, say 60 amps, for extended periods of time or will it burn out the diodes, bearings etc? "
They should be able to do that continuously.
"Do automotive alternators have built in regulators or are they external "
The come both ways. They regulate the current which is sent to the field which controls the flux through the stator coils.
"What does the regulator look at to determine charge rate?"
Battery voltage.
Here is an argument against persuing this much further.
They wont be very efficient, especially in low winds. Since they do not contain permanent magnets, the field (which is how they are regulated) is a big electromagnet - which draws power. The first 30 - 50 watts you generate is required to energize the field of the alternator. That's power wasted... and in most medium/low winds... it may be most, if not all your power.
They like to go real fast, so you will need to gear (belt) it up significantly. Figure you have something like an 8' prop (a reasonable size for a car alternator probably)... in low/average 10mph winds, you may have 100 watts available at the shaft or so (if its a good prop). Thats about a 1/8 HP motor! Your belt will suck it all up - if not, energizing the field will.
Between energizing the field of the alternator, and the belt - it will probabably perform quite badly except in strong winds.
The regulator that goes with car alternator would not be appropriate... it would disconnect the machine from the load when the batteries were full, so that your wind turbine blade would be "free-spinning" - which is usually a dangerous and noisy situation. Most wind turbines are regulated by dumping xtra power into a load... usually a heater. The wind turbine should always be hooked to the batteries and always under a load.
So while I think a car alternator could work, I believe there are probably much better solutions. When you consider the cost of a tower, batteries - building a machine etc... it doesn't make sense to me, to build around a car alternator and wind up with a highly compromised design.