For a rushing QB it depends on what direction you want to go. Personally, I think it's very natural to build a spin-oriented rushing QB.
You can relatively easily build a 145+ speed/105+ agility/80+ strength/77+ carrying/60 vision rushing QB with Spin/Juke. It isn't super conducive to a positive EL, but maximizing the speed/agility/strength/carrying attributes is the way to go.
To your second point, there are multiple scripts that spit out the remaining ALGs for you. If you want to calculate it manually there is a handy chart here:
http://wiki.goallineblitz.com/index.php/Natural_growth#Value_of_Attribute_Increases_.28Rounded_to_the_Hundredth_Decimal_Place.29