Hello Alex,
Good to see a QTP guy having keen interest in Selenium.
I hope you have seen Selenium Doc which is available at -
http://docs.seleniumhq.org/About how much oops to learn, this post might help -
http://www.seleniumtests.com/2011/06/beginner-to-selenium-where-to-begin.htmlThere are few Selenium frameworks (including Keyword) I listed here, you might like to read more about them -
http://www.seleniumtests.com/p/selenium-frameworks.htmlHope this helps
~ seleniumtests.com