You don't need to buy books. All you need is to collect enough Ninja Fragments for a book to be activated.

Ninja > Training > Breakthrough.

You can choose to update your Sasuke to version 1 or 2.

Version 2 is where your Sasuke's barrier won't disappear, unless it was taken down by someone such as Roshi or Tendo.

Version 2, also allow your Sasuke's chase to use Chidori Stream as you may have seen in Orochimaru's TI.

There is a ninja skillbook somewhere online you can look up. I dont remember where. I'm sure you find on Google :)

For me, I am still deciding whether I should go version 1 or 2.