Weight is not really a factor.
While I agree with much of your advice - I'll take slight exception to the above comment.
Weight is a very important factor in two, mutually opposing, regards.
First, more weight = greater stability. The lighter the tripod, the greater it's propensity to react to ground shake (foot traffic, cars, whatever) or wind, or even camera shake form the mirror reflex.
Second, less weight = easier to lug around.
A tripod is the single best way for a photographer to reduce or eliminate blur caused by camera movement. I would argue that the photographer intending to buy a tripod should get the best,
heaviest one that he/she can afford - and can feel comfortable lugging around.
I have two tripods. One very lightweight that collapses quite small. Good for sticking in a bag when we're walking around. Because of it's light weight it is not the most stable, but it works and is easy. The other is a high end, heavier, tripod that I carry only when taking my camera backpack and know that I am going to need it. Again - it is not the heaviest on the market because I have to carry it in a pack - but it is relatively heavy and keeps the camera still in all manner of circumstances.
Two other great ways of reducing / eliminating blur due to shake:
- Remote shutter release.
- A camera that allows you to lift the mirror before shutter release.