Botulinum Toxin in Home-Canned Green Beans I was given a jar of home-canned green beans.  The method of canning is unknown.

Wikipedia says:


  Botulinum toxin is denatured at temperatures greater than 80 °C (176 °F).[27]
  
  Proper refrigeration at temperatures below 3°C (38°F) retards the growth of Clostridium botulinum. The organism is also susceptible to high salt, high oxygen, and low pH levels. The toxin itself is rapidly destroyed by heat, such as in thorough cooking.[30] The spores that produce the toxin are heat-tolerant and will survive boiling water for an extended period of time.[31]


As usual with wikipedia, I'm not able to view the references.

My questions are:

1) At what minimal temperature and for what minimal amount of time is that temperature to be maintained to destroy the toxin?  I'd like to see something definitive and believable.

2) Suppose the toxin is destroyed by cooking, but the spores remain.  What is to stop the spores from becoming newly toxin-forming bacteria in my gut?  Is there not enough time?  Is there suppression from beneficial bacteria which prevents it?  Is the ph wrong?  The temperature?  The oxygen level?

3) If you've answered the first two questions favorably and were presented with a can of beans having a somewhat more than remote chance of containing clostridium botulinum, would you follow the procedure in your answer and eat the beans?  Assume you like green beans.  I don't want to see "when in doubt, throw it out" because shouldn't there always be an element of doubt with anything home-canned?  Shouldn't we treat each jar as if it was known to be contaminated?  I understand that there is an extra element of doubt if the canning procedure is not known, but then again, if the sterilization procedure works, does it matter what process was used?
The only way to prevent botulism in canned foods is to either make it to acidic for the spores to survive, or to pressure can it using the right equipment at a temperature of 121C for at least 3 minutes. If this hasn't been done then it could be full of botulism, in which case simply cooking it above 80C for say 30 minutes just to be sure (that's double the 15 minutes I've seen recommended on some sites, I'd take no chances) - as you say will destroy the toxin. If you eat it right away afterwards then you'll in all likelihood be fine, it takes a couple of hours at least for enough toxin to build up to be harmful, even in ideal conditions for it to develop. 

However, if there was a chance that there was botulism in home-canned food given to me I wouldn't take the risk. Even though I know scientifically that I would be safe by following the above advice I wouldn't be able to enjoy the food, every bite I'd have nagging worries that I'm poisoning myself. If I was starving I would in a second of course, but I can walk to the corner store and buy all the food I want so why take the risks? 

I wouldn't hesitate to try home canned food made by someone who knows their stuff, but if there's any doubt of the provenance of home canned food then the best advice would be to throw it away.