Well I don't know what would make 15.90 a magic number other than a guess. If you like the deal you would be much better off selling VSLR and buying into SUNE today, rather than waiting for pennies, or maybe nickels and dimes by the time this deal closes.
Yes, but there is no upside. SUNE going up adds no value to the deal - actually gets you less in stock and Notes. You are holding the stock for who knows how long, with no chance of appreciation. In that situation you are better off with a current value of SUNE stock as you have chance of appreciation rather than dead money for months. That's why VSLR will not EVER price at 16.50, barring a rival bid.
Because the price was not locked in at Fridays closing price of SUNE. For VSLR shareholders that would have provided upside if SUNE continues higher. Now just the opposite, the higher SUNE goes, the less SUNE stock we get, which keeps the price of VSLR lower.