Top speed is 8mph according to my Iphone loaded with the tomtom app.
As for seating, there is a 14" gap between the end of the seats and the rail on the port side. Admittedly, you have to turn sideways to get by the seat, but everyone seems to cope!
And no, I haven't convinced my wife to get on board, but she only likes the pontoon. The neighbors thinks its great though!