Your preboil volume will be more than the pot, Mine is about 13.7G if memory serves me correctly. I have a 15G pot and would definitely recommend a 20G pot for 10G batches. You can do 10G in the 15G pot but you have to watch it VERY closely.
i did a 12 gallon batch in a keggle. We did a 90 minute boil, and after 45 minutes of the boil, we added the rest of the runnings. There was risk of getting DMS from not doing a full length boil on the entire volume, but the beer came out great.
I am a big fan of the antifoam. A couple drops in the boil makes all your boilover fears go away. You can also have a small fan blowing on the surface of the boil and that will both prevent foaming as well as increase the evaporation rate.
That said, you should probably not put more than 11.5-12 gallons in at first. The suggestion of adding some in 1/2-way through is a good one.