| My two main bows are a Prochownik (from Winnipeg) at 133 g, and a Reid Hudson (from Duncan, B.C.) at 130 g. Both are french bows (although I also have a Prochownik german bow, 127 g).
The Prochownik sounds much better with my bass, although I much prefer the feel and response if my Hudson. I suspect the lighter bow feels better because it is a little lighter, but I'm less convinced the tone of the heavier bow is better because of the weight. There are way too many chance variables for me to generalize too much based on these two bows.
I do resist the notion that heavier bows are generally louder. Many people seem to think this, but I'm not so sure. Your arm is way heavier than any bow, so I suspect a few grams here and there between bows is going to make a negligable difference when compared to the weight of a really relaxed bow arm. Weight will affect the balance and response of bow IMO. Heavy bows (around 138+ grams) make me easily fatigued and tend to be much more sluggish for quick strokes.
I do think it is very important to judge each bow as an individual entity, since even identical weight bows from the same maker can sound and play very differently.
Regarding length - I don't know - I've never really considered the issue before. | 
