93 Passat smoke under hood

Hi all, just bought a 1993 VW Passat GLX V6, 170,000 miles. Looked
good, test drive for half hour in various conditions.

Drove for two days before white smoke started coming out from under the
hood and through the A/C vents; temp light came on. Pulled over
immediately and had it towed to my mechanic.... who was on vacation.

Next day drove it a few blocks to Jiffy Lube and on the way it smoked
again. I stopped and checked the coolant level and there was hardly
anything in the damn thing! Construction guy on the road dumped water
into it and I headed to Jiffy Lube; changed oil, told them about what
happened, they said they filled the coolant and I should be alright
just have it checked when my mechanic gets back. Sure enough not
halfway home the smoke started from under the hood again.

It looks like smoke, not steam. Under hood every time and through the
vents the first time while A/C was on; left A/C off after that. Hard
time distinguishing smell; kindof burny possibly electrical but I'm not
real sure.

Took it back to my mechanic who got home this morning; right off the
bat he found a coolant leak where a hose connects to the thermostat
housing.

Could there be something else going on as well? Any questions I should
ask my mechanic? What do you think I should expect? I want to do some
research on my own, not just take one person's word for it - you never
know.

Thanks much,

Cris