a; No contest power wise, a stock "derestricted" mc21 will give 58-60 bhp for nothing, an mc28 in the same spec will probably make 52-53 at best. mc28's are getting real expensive now too, but may sell easier if you decide to sell.
b; Just normal stuff really, but they aren't hard to fix, don't panic too much as long as it's straight and starts, even a total lemon can't be that bad.
c; I'm a spot under 6ft tall, Andy is similarly sized, we fit on them.
d; You're a married man with children, of course you're mad. Honestly I don't know why people worry, these bikes are not hard to fix.
_________________
Please do not PM me technical questions, if you can't find it on the Forum start a thread