CONCLUSION:
Over-nervous new owner. After 2 hours on the lift yesterday, we determined that the "bubbly/foamy" stuff in the coolant was actually remant detergent bubbles from the earlier engine replacement and system cleaning/flushing(!). My Porsche mechanic said he had "never seen this before" but it didn't seem to bother him, and it was a huge relief to me.
Then, the substance I saw in the oil filler tube was a normal residue/by product of someone (me) driving the car a very short amount and then running to the engine, looking in, and finding condensation, yellowish residue which apparently is totally normal.
The smell. We found evidence of coolant fluid burned up on the headers. Apparently the overflow drain empties right above the headers on this car (I have a Fabspeed upgrade). So, the seller had just had the 90,000 mile service done so more than likely when filling the coolant tank, he spilled a little.
Lessons.
-I learned a lot. I definitely over-reacted but I'd probably react the same way under the same circumstances again. The car is awesome, it's not perfect but then again it has 90000 miles and a replacement engine at 53000 miles.
-use Porsche coolant, apparently it is recommended. If/when you need to flush system, flush it with detergent and then get the detergent out (if possible).
-I have 2 very very minor outside oil seeps, one at the RMS, and I think this is normal (I hope it is) but the oil in the car looks perfect and other than the detergent remnant in the coolant tank, the coolant is clear as well.
.
The water-cooled 911s used to tick like a time-bomb for the first ten minutes or so after switching off the engine after a fast drive. I never noticed any other car model do that, but it was perfectly normal for the 911.
