Wishing I had my copy of Basic Aerodynamics handy to provide some more detailed references and numerical examples (may come back later to add more detail), but here goes the highly abbreviated version.
Airfoil shape is absolutely critical in determing the distribution of lift (and therefore air pressure differential between the two sides of the wing) and this holds true for literally anything that makes use of them. The exact specifics as to how much this varies differ from one airfoil to the other, but you should be able to just look up the airfoils you're interested in and compare their coefficients of lift, one of the variables in the generation of aerodynamic force (i.e. horizontal lift and induced drag), at various alphas (a.k.a. angle of attack, angle of incidence).
The coefficient of lift is indeed determined by the angle of attack. The greater the angle of attack, the greater the coefficient of lift, right up until the point where airflow separates from the wing and you enter a stall. The end result is that, for a given airfoil and constant airspeed, the higher the angle of attack, the more lift your wing will generate, and the greater the air pressure differential.
A very interesting question and the answer is, it depends. For a constant camber airfoil (think your basic Hershey-bar style wing), you should be able to get more lift being generated closer to the wing roots. This happens due to the fact the airflow tends to "slip" around the wing edges due to the fact that we do not have infinite span wings and the higher pressure air underneath the wing tries to fill the lower-pressure areas on top and has an outlet to do so where the wing ends. The end result of this phenomenon is known as a wingtip vortice and one of the effects is that the aerodynamic force vector usually has a somewhat different direction at the wing edges vs. the tip, usually leading to less vertical lift being generated their as opposed to the wing root. Other things to keep in mind, many modern manufacturers will use variable-camber designs today to build wings that stall at the wing root first in order to ensure aileron control as far into the stall as possible. Recommended further reading on this topic: wingtip vortices, wake turbulence, winglets, Spitfire wing
For most subsonic airfoils, the center of pressure will occur quite close to the leading edge. Again, this depends on the wing design itself, which is dependent on aircraft role and requirements. Aircraft designed to fly slowly will typically have relatively "fat" wings with a pronounced camber close to the leading edge. Aircraft design to fly faster will seek to reduce frontal area and will have their thickest camber set farther back. Supersonic airfoils generally have a vaguely diamond-shaped profile owing to the need to keep the leading edge very sharp and the frontal area minimized.
If I might suggest, if this is something you're curious about, look into picking up an introductory text on aerodynamics. The topic is truly fascinating and the answers to your questions can run very deep indeed.
In the meantime, hope this helps.
@erich @FreeMan I've been doing some thinking about the 747 question and I think it's worth delving into some of the underpinnings to clarify a few things.
Disclaimer: My expertise here is as a pilot rather than an aero engineer (big, big difference in the depth of study of aerodynamics), so if any mistakes follow, that's why.
One thing to remember about an aircraft in flight is that it's not so much air "flowing" over the wing, as the aircraft "flowing" through the air. We often illustrate air moving over the wing because this is how it works in wind tunnels and, as an added benefit, it simplifies things when introducing this topic to new students. We often use the term "Relative Wind" to refer to this phenomena.
As such, it is important to remember that when the aircraft moves through the air, it displaces air and pushes it above and below the wing. To further simplify our discussion, let us assume a positively-cambered wing at 0 alpha. What will happen in this situation is that the surface area on the top of the wing, being greater than the surface area below the wing, will have fewer air particles per unit of area leading to lower pressure on the top of the wing than the bottom, as air density is relatively constant around the aircraft. This pressure differential results in a force, whose vertical component counteracts the aircraft's weight, resulting in level flight. Extrapolate from here for climbs, descents, banking turns, etc.
Digression: you may point out that if this is the case, how come airplanes don't just sort of float away when they're on the ground, seeing how the wing area differential still holds. The intuitive reason for that is that unless the aircraft is moving and "disturbing" the air around it, air particles will be free to float around the wing and fill any low pressure areas until the pressures equalize.
Going back to our 744, what you would really be interested then is to actually calculate pressure differentials and, working from there, calculate "speed" differentials (keeping in mind that you would actually be calculating more of an "average speed", as different parts of the wing will generate different amounts of force). Someone else will have to do that math however, as I can't seem to find the necessary technical data. Also, in case you're wondering, yes, the fuselage also generates a certain amount of lift, while the tailplane horizontal stabilizers generate a aerodynamic force downwards (think "negative lift"). Have fun digging :)