1996 854 Turbo purchased at 110K in January 2005. Oil changed at purchase to 10W-30 Castrol and installed new t-stat, timing belt, abs control unit,strut caps, turbo oil line, flushed transmission, and antifreeze. Checked oil every 400 miles to monitor usage and up to 1800 miles - minimal oil useage, and was full to mark and dipstick clean.
Have had slight antifreeze smell at initial warm-up from heater vents, but no condensation on windows (Wisconsin winter) or interior dripping/leaks. Probably after heater core heats up, small cracks reseal somewhat. Plan to change with FCP Groton core (recommended onnother post)

Now to problem. Last Wed 3/23/05, Radiator low coolant light came on at start-up and went out at warm-up (after expansion of coolant). This happened several times that day. Thought was due to heater core -but with no dripping probably not.Checked radiator fill/expansion tank and it was empty! Checked oil (112.4K) with 2400 miles and was slightly down 1/4 qt. However, light tan foam was all the way up the side of the dipstick. Rechecked "oil level" oil from pan on bottom of stick and it is still perfectly clear, amber. Car idles smoothly and good power. Not really sure if exhaust has condensation -doesn't look different.
Inside of oil fill cap is still clean, no residue.
Don't know how long this has been going on, but dipstick was clean when I checked oil several weeks ago so it can't be too long.
Have parked car and will not drive till resolved

My first thought was HEADGASKET, however after reading all antifreeze, headgasket posts, I'm not sure??
Advise/experience please.

Also, is the foam and antifreeze damaging long term after the head gasket or whatever is wrong is fixed. As there would still be some residue present? Is any cleaning/flushing required?