I'll draw a lot of flak for this, but choosing between a 30-'06 and a .308 is like choosing between a Honda Accord and Toyota Camry. They're about the same price, have the same basic level of performance and the only place you would notice even a paper difference is with bullets weighing 200gr or more. In a nutshell, unless you're planning to hunt bears or maybe moose, the .308 will give you what you're looking for and be a better target rifle, overall. If you'll be going after bigger critters, and won't buy a gun specifically for those hunts, then the '06 will give you better versatility, with heavier bullets.
As for the scope mounting, I think that will depend entirely on the gun/action you select.
As for the scope mounting, I think that will depend entirely on the gun/action you select.