RE: Effect of too much nose weight
The biggest thing you will notice on landing is that the plane doesn't want to slow down. You'll find yourself over-shooting the runway a lot.
Being nose heavy will also increase the stall speed. So, for example, let's say that "Plane X" has a stall speed of 20mph, and you can land it comfortably at 25mph (5mph over stall speed, or think of it as a 5mph cushion). Well, now it has a stall speed of 27mph, but at 32mph it still want to fly when you try to flair. You find that at 29mph you can get it down, but it's faster than you want to land, and now you only have a 2mph cushion.
It can really drive you nuts and cause you not to like an otherwise perfectly good airplane.