Pigboat, I feel lucky to meet you on PPRuNe!
Thank you for the good explanations.
I must say that I still feel that to land and take-off a seaplane is probably more risky than for normal wheel plane. The condition of the water rough/smooth, the waves, the position of the floats on landing etc. I think with wheels on tarmac it will be easier but I suppose with practice you can learn to make it safe.
The Norseman take off was very very long indeed but nice to watch.