1988 Ranger v6 with oil / antifreeze mixed

I have a well cared for '88 Ranger XLT with 134,000 miles on it. Last week i had overheating problems. I filled the radiator w/ antifreeze and water, and looked for leaks. oil was fine. The truck ran fine except I overheated again. Although I didn't see a radiator leak, I figured to add more antifreeze /water mix and also changed out the thermostat for a new one.
Same day i changed the thermostat, I drove the truck for about 20-30 minutes, and got a small billow of smoke (it was night, so i couldn't tell which color) out of the muffler. The truck got me home another 5 min drive though, with not much different reaction from the engine while driving.
Next day it wouldn't start. I checked the oil and had the dreadful peanut butter color and was way overfilled. I pulled a spark plug and it looks a little fouled, but not too bad.
After draining the oil, flushing it twice & changing the oil filter, i have new oil in there.
The truck starts right up and sounds fine... The guage doesn't show overheating anymore, but after running the engine for 10 min or so, i get burnt oil coming out.
I topped off the Radaitor fluid and check the oil for mixing again.. They don't appear to be mixing anymore.
QUESTIONS!
1. Is it possible I had a bad thermostat all along and overfilled the radatior by accident? would this get into the engine?
2. I am paranoid to drive it to a shop, thinking i might do more damage? but maybe the current smoke is just from spillage of oil?
3. If i blew the head gasket, wouldn't the antifreeze continue to mix with the oil??
thanks for any help you give me. I love this truck as it is in very good condition all around and of course can't really afford to get a new one. THANKS,
Andy

Just ran the engine for a bit longer.
The burnt oil seems to be coming from the outer parts. I've taken the oil cap off and seems that there is no soke coming from inside.
Also, after running it for awhile I checked the radiator coolant level, and it looks like its a lot lower than before I ran it. I will check after it cools down again, but should what is the best time to check your levels of coolant??
THANKS
andy

Sounds like a head gasket. Do you get bubbles or bubbling in the radiator with the cap off and the engine running? If you pull the plugs you should be able to see one or more plugs very clean. (steamed clean) The coolant probably leaks into the crankcase when the engine is off, and steams off while the engine is running. Smell your exaust, if it has a sweet smell its antifreeze. I would'nt keep running it, water in the oil is a bad thing. Put a pressure test on your cooling system to verify.