I've been to Lusaka a few times and like it a lot. Cool people those Zambians ^

I can just agree that the water level in Oct-Dec will probably be low and you will not see a massive waterfall. Lusaka nightlife is as said these shopping malls. Many restaurants and I remember Rhapsodys to be the posh place in Arcades shopping mall:

http://www.zamazing.com/rhapsodys.htm

Getting to Livingstone is easiest by car, takes a few hours but is a smooth ride. Plenty of police trying to fine tourists so watch the speed.

Livingstone itself is not much to see. It has an interesting train museum though where you can explore the colonial time trains ^

A large luxury hotel is located just outside Livingstone on the road to Victoria falls. I can't remember the name but it was impressive with a huge pool area. So I would recommend a car trip as you need the car to get around anyway.

Ah, I almost forgot. The booze cruises on Zambesi river is a must. Go with African Queen. You pay a flat rate and drink as much as you want and watch hippos, crocodiles and elephants ^