I also think I know why you didn't get the achievement for Bleak Falls Barrow. there is a quest in Dragonsreach that also sends you there. You'll be ok if you picked up the dragon stone. If not you'll have to go back.
Also, outside Whiterun is the Whiterun Stables. You can't all to the guy sitting in the carriage and he will take you to some of the major holds for a fee. Once you know a location, it is white on your map instead of black. You can click on white locations to instantly fast travel there (time will still progress in game). Helpful for going back places like Bleak Falls Barrow for that stone you missed lol
