>15. Can you recommend any good tutorials on OOP and C#?

http://www.csharpcorner.com/

http://www.csharphelp.com/links.html

Or a good search engine...

>16. What about books?

Starting Out with C#
Beginning Visual C# 2005
Visual C# How to Program, 2nd ed.
Beginning C# Objects from Concepts to Code
Learning C# 2005

A lot of reference books are good and some are bad- depends on what you like..

>18. Should I learn the basics of C++ and/or Java to get the OOP feel first, or can I just go to C# directly?
Agree, with Prelude above- but to fully answer that I would need to see how "newbie" you are- i.e. learn quickly, etc...