RE: 10 ft. Tap rule - (you should take a look at 240.21(B) for specifics)....IF the size of your tap conductor is rated at only 1/10 the size of the conductor you are tapping, then yes, you are limited to 10 ft.
However, if you increase the size of your tap conductor so it is sized at 1/3 the ampacity of the conductor you are tapping, then you can increase the distance to 25 ft. [see 240.21 (B)(2)].
If these tap conductors are running on the outside of the building, then you have unlimited length [see 240.21(B)(5)].