I think you max out the pop bumpers by shooting the left loop(between the pops) after a certain number of loops thru you light one more then the next one till they are all lit - can't remember the value it puts for each lit pop but - thats about as much as I have figured out. I dont think the top pops and the lower ones have any relationship

You are better off missing the skill shot on a soft plunge then hitting the targets just above - if you hit the targets above, it turns off ball save and its a dangerous shot. If you miss the skill shot because its not hard enough you can let the ball drain and try again, assuming it doesnt hit an outside lane switch.