The epoxy is not burn or cut resistant. You shouldn't be cutting directly on your countertops anyway. It is not heat resistant either. I've had to repair one where something hot was set on it and it caused an ugly bubble. I was able to cut the bubble out, fill the hole and then apply a new coat to the whole top. You had to look hard to see where the repair was made. My customer was very satisfied.
Any of the epoxies that are a bar type finish will work no matter what the brand. They are all food safe to my knowledge also. Some paint stores carry it or you can purchase it online.
I would not attempt an undermount sink. I can forsee too many problems and personally I would refuse if asked to do it.
Here is another kitchen countertop that I just finished about a month or so ago.