I have my regular google calendar synced. Google now has the Sports calendars which we can subscribe to (I've subscribed to soccer) - this one does not sync.
beacuse if you don't change your default calendar to the caldev account what you update on the iphone won't update google
you will always have an iphone only calendar and now you have a iphone/google calendar. it defaults to the iphone only calendar. if you don't change the default you will have to manually change the calendar every time you want to update it
yes you can use the MS exchange with google sync. however this takes up your only ms exchange account. in the future you might want to put an e-mail there. maybe for work or something......