1) Pick either c# or javascript. c# is a little harder to learn at first, but you get the benefit of tutorials on how to use it, javascript is a unity specific language with no real language documentation. If you pick c#, don't pick c++, they're not really that related besides the c in the name
2) Most bookshops with technical sections will probably have c# books, otherwise amazon and the like definitely does. For tutorials, they're everywhere, google is generally your friend there (Type in c# tutorial and you'll get a bazillion links).
I found these tutorials at http://www.unity3dstudent.com/ to be the best.
They all video tutorials and they go quite a bit into scripting with simple line by line examples.
If you are interested in game development, you might also be interested in our online 4-day course on Game Development with Unity: http://gamedevtraining.zymichost.com
Its interactive so you can ask questions from the instructor, and share your screen live. Its only over weekends, and since we are doing this live for the first time ( we usually do in-person), its very affordable.