You know what play I am referring to when the player more or less hides on the sidelines then goes out for a pass this is illegal right?? Also so I understand this right a fullback leading a sweep for his tailback cannot block below the waist is this correct also?

Yes. Hiding a player on the sidelines is illegal. If the defense sees him and covers him then you might not get a flag but you should be told not to do it anyway.

His initial contact can not be below the waist. If his initial contact is above the waist then he can, while maintaining contact, move down below the waist to continue the block. The hands are also considered part of the body which is above the waist. If the defender tries to push the blocker away with his hands then the block is considered to have started above the waist and, if contact is maintained, may move down onto the legs.