In my day a good listing at dmoz was priceless. One of the first things I did after I figured that out was apply to be an editor there. I was one for years in top level adult gay categories. I rarely used it to my advantage but when I did it really paid off. The editors there are very corrupt though, probably because the space is worth a lot of money. Control of listings there is extremely competitive. I have no idea what advantages there are now to getting your site into dmoz but when I became an editor there in 99 there were too many to count.

As far as the time it takes, most categories and subcategories have different editors, and the editors change over time. There is never any way to guess how long it'll take, unless you've recently submitted some sites to the same category. Even then it's pretty random.