Your pattern may tell you somewhere what they mean by the different abbreviations. In my experience a C4F means a cable cross involving 4 stitches that holds the yarn in the front as you work. So you'd move 2sts to a cable needle, hold them in front, knit 2 then k2 from the cable needle.
(k1, yo, k1) in next st.
You are going to do what is inside the parenthesis into the next stitch. So knit it, but don't take it off the left needle, bring the yarn to the front (the yarn over) and then from there knit the stitch again, now let it off the left needle. You have made 3 stitches out of the 1, increasing 2.
I'm not sure. The C4F was a left cross, so if they wanted a right cross I don't know why they wouldn't have called it a C4B, as that makes a right cross, but maybe that is what they want. That would be move 2 to cable needle, knit 2 holding in back, knit the 2 from the cable needle.
But again they may tell you somewhere what they mean. If it is a book there may be a key somewhere, or a website, same thing.