Some really basic help

I am fairly new and need a bit of information.

What exactly is rr?
What exactly is PK?
What does the abbreviation ft mean... ie   ft joh (jewels)
How do I activate my SD
Sometimes other characters kill me, but for some reason I cannot attack other characters
What are the skills I can put in my list.. the ones where I use ctrl-(plus number) because I cannot get that to work