[MagicRat]

As I posted in another thread one of my cars has the same concerns.
It sounds as if your diagnosis is correct, the engine is burning coolant. Chances are that bit of white smoke under the hood is blow-by gases, that is, combustion gases are seeping past the piston rings and getting into the crank case.
Some blow-by is normal, but usually you cant see it because it is vented into the engine through the PCV valve and a vent tube which goes into the air cleaner or intake manifold. Perhaps this vent tube has fallen off, so you are seeing the smoke. If so, it shoudl be reinstalled.
Now, since burning coolant is unusual, some bad things are happening: 1. The oil is becoming contaminated with coolant, which will eventually shorten the life of the rest of the engine. 2. Burning coolant will contaminate the catalytic converter and oxygen sensor, reducing their effectiveness. 3. Burning coolant has glycol, which is poisonous, if you breathe enough of it in. 4. The problem will only get worse and might leave you broken down and stranded somewhere.

You need to get this fixed by removing the cylinder head and replacing the gasket. Have the head thoroughly checked for gasket surface straighness and for cracks. Have the mechanic check the engine block for cracks or damage, (although this is rarely the cause for such problems.)
Rebuilding the head is a good idea, as often, oil burining problems can be traced to worn valve guides, which are in the head. This is the time to get that head thoroughly rebuilt to correct all these problems.