p = pull off. 5p3 = this is just the opposite of the hammer on. put your index finger on the 3rd fret AND your ring finger on the 5th fret. Play the string and then pull your ring finger off the 5th fret.
b = bend. (notated many different ways) = Try this first on the 7th fret on the G string (3rd from the bottom). Put your ring finger on the 7th fret and push the string up, or pull it down if that's easier. This will make the note raise in pitch. There are different kinds of a bends: A FULL bend is one that goes up a full step or two frets - when you do this you push the string up/down until you play the note equal to two frets above that fret. The other is a HALF bend which is just pushing the string up untilyou get the note of one fret up.
/ or \ = slide 5/7 or 7\5 = All that this means is to put your finger on the fret indicated by the first number, play the string, and then slide your finger to the second number. for the first one you'd put your finger on the 5th fret, play the string and then slide your finger to the 7th fret WITHOUT PICKING YOUR FINGER UP.
Anyways, I hope that helps with your questions on what the techniques mean. I'd be happy to help you some more if you need it just send me an e-mail - david@guitartricks.com