...the changes you have listed won't change much, (in my experience). Personally, I do find that getting a longer stem and better overall fit on a straight up quill stem road bike usually helps me to redistribute my weight a little better over the wheels, and I do notice that. I don't have a whole lot off personal experience with changing stem angle by 10*, but in the one or two instances I've done it, again I noticed little other than better anatomical fit, and better weight distribution.

A stem that is too short will tend to make you ride more upright, so you have a tendency to put more weight over the rear wheel.

FWIW, you can also fool around with saddle position fore and aft, and see if that helps or not. The whole thing off finding proper fit for you is a process, and you might need an even longer stem for optimal results. Once you have something that feels right for you, measure the distance from saddle (at the post) to centerline of the bar. Then measure saddle height at the top down to pedal contact surface. Those are the numbers you need to set up another bike at the start when you are figuring it out at the beginning.

The numbers are different depending on the purpose for the bike (racing, touring, around town and more upright, etc.)