and what's your definition of those on another planet that doesn't have a magnetic pole ? Is the "North" the "top" of the rotation - which way is the top ?? (here's a link that shows what a compass would do on the surface of Mars : http://mgs-mager.gsfc.nasa.gov/publications/grl_28_connerney... )
You know Earth's magnetic poles don't match up with its rotational poles right? They're kinda close, but the magnetic poles wander. Even though Mars (oddly) doesn't have strong magnetic poles, that doesn't mean it doesn't have poles. As for which one is north, we just pick a direction of the solar system to be "north". http://en.wikipedia.org/wiki/Poles_of_astronomical_bodies
I would guess that we now name the "north pole" on any planet that which your thumb points when doing the right hand rule with the rotation of the planet... but I'm not sure.
That's used for moons and dwarf planets etc. But in this solar system, we actually have a designated hemisphere that is "north" for planets. It's explained in that link I posted.
The orbital axis of all the planets in our solar system are roughly parallel (within 10 degrees, Mars is just under 2 degrees off ours), so it would be fair to pick a north pole at the same "end" as ours. http://en.wikipedia.org/wiki/Orbital_inclination
The article you linked to describes the angle of plane of the orbit - the circle it makes around the sun. These vary by only a small amount.
The axial tilt is different. It is basically how far the axis through the poles of a planet is tilted compared to the plane of its orbit. This is what you were thinking of initially - it can very a lot.
