Gasoline is a mixture of the alkanes and unlike many chemicals, can be stored for long periods and transported without problem. It is only when ignited that it has enough energy to continue reacting. This property makes it difficult for alkanes to be converted into other types of organic molecules.
Recovery from being spayed is usually around 10 days. My kitten was back to her usual self in three days but it took 10 days for the incision to heal enough for the stitches to come out.
The best time is at 5 to 7 months of age before the female cat goes into heat for the first time. Sometimes vets do it as early as 7 weeks of age. The vet authors of the above mentioned book say that early spaying does not cause health problems or long term behavioral effects. Hope this helps.