Plenty of eating to be done in St Andrews, I quite like The Tail End eat in chipper.
Bit further afield, keep an eye out for Sea Eagles at Tentsmuir and all along the north coast of the kingdom.
The coastal path south of St Andrews is a nice but linear walk, I've done a training run from Dundee to Elie on the Coastal Path and apart from Leuchars to St Andrews it makes a pleasant enough outing.
Elie chain walk is a good laugh, albeit short
Pitenween Chococlate shop, Anstruther chipper, boat trip out to the isle of may is a nice half day out.
Lomond Hills have some reasonable biking/running/walking, as does Pitmedden forest south of Newburgh.
I'd have said it'd be better as a family trip rather than a mates one. Unless you like Golf of course.
Prepare to be considerably poorer.