PackageManager.FeatureTouchScreen - Touch is available
PackageManager.FeatureTouchScreenMultiTouch - Two finger gestures
PackageManager.FeatureTouchScreenMultiTouchDistinct - Two or more fingers independently
PackageManager.FeatureTouchScreenJazzHand - 5 or more fingers independently
Android doesn't provide a property for a more specific maximum, and I don't think it defines an overall max that devices can provide. I think most current Android phones support 10. Assume infinite are possible even if the app only tracks fewer - bounds check and discard values out of range rather than crashing.
I used to have a 30 touch-point screen, and my colleagues and I surpassed that number with multiple people finger-painting at the same time. My painting app lost track of the extra touches, but it failed gracefully and didn't crash!