Adding pedals & training wheels to this balance bike?
You could probably add training wheels, but not a crank.  There simply isn't anywhere on the frame for cranks to go.  Also, adding training wheels to a balance bike is kind of defeating the purpose of a balance bike.  It's meant to be an alternative to training wheels that allows the child to learn to steer into falls and "scoot" around and eventually learn to glide around before riding a bike with cranks on it.  These have been pretty universally hailed as the best way to teach a younger child to ride.  Oh, and with the shape of the frame, you may not be able to find an appropriate set of training wheels too, they would end up at a forward angle, and would be more likely to get in the way of the "scooting" action kids do on these bikes.