This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Yes it is, but you only have to know a bit of the basics.
You should know that your tag exposes a variable that can be used in the rest of the page. The <scope> defines where you can use that variable.
What part is confusing for you? Have you tried creating a tag and exposing a variable?