[RLKBOB]

One valve cover should have a pcv valve hooked up to engine vacuum on the intake manifold and the other valve cover should have a breather filter. The side with the pcv valve is keeping a slight vacuum on the crankcase and the breather filter is constantly filtering and letting in new air to replace what's being "sucked" in the intake. If you don't have it set up like this then your crankcase will maintain a positive pressure and blow out oil and possilbly other stuff.

 

[RLKBOB]

That breather on the drivers side is fine as long as you have a properly working pcv valve hooked up to manifold vacuum on the pass side.

 

[RLKBOB]

You can use fuel line. 2 things to do to check the pcv valve. Shake it and make sure you hear the ball rattling around in it, if not get a new one. Also with the pcv valve hooked up to vacuum and the motor running pull the pcv valve out of the valve cover grommet and put your finger over the end you should feel the vacuum sucking it to your finger, if not get a new one.