Welcome, MPG will depend on you, I can usually get about 32MPG, your results may vary.
As for the Busa not turning, tell whoever it is spouting this nonsense that they are full of sh*t and have no idea what they are talking about. Is it a track tool, NO, but you will be amazed at just how well it handles. Turn in is pretty light, and it tolerates mid-corner adjustments very well. Only thing I have really noticed is that the factory settings for the suspension are a bit harsh, for me anyway 215lbs. But really the thing isn't really designed for lightning quick transitions but it will out handle your Katana 600. It's relativley cushy and is an absolute rocket sled.
Now I know you are 33 but I have to ask anyway have you been to the MSF yet? If not I highly recommend it. Also take it easy on the Busa at first, following the break in requirements to the letter will help you there. Once it's Broken in and you are ready to rock just remember to hold on tight...seriously...when your rockin through the gears it will surprise you just how hard it pulls. Enjoy it and treat her right... Your going to have a smile stuck on your mug till it hurts. Promise...