Power Scroll[2] can be bought from the Skill Masters in Elderine. Might be on the second page. The Shield Increase[2] has to be obtained from mob drops. They are rare drops... or you can buy them from players though I don't know how much they go for in Teva.
All drops occur whatever level you are and is not limited to what sort of skills you have learned.
As for licenses you can go to our Wiki page:
Licenses.
Check the Wiki for various other information, it's very very helpful.