Lambert,
your boats impeller is always turning, even when in neutral (obviously when the boat is running). So there is always water moving out of the pump(s). When in neutral a "gate" covers and re-directs the water from the pump so that it's not pushing you forward. But you might need to look at the "gates" and see if they are properly adjusted for forward/neutral/reverse.
As far as the rope in the intake. When you get the boat out of the water, take off the intake grate and reach your hand in there and try to remove or cut the rope out of there...
hope this helps,
Ryan