As to a tripod, I would look at your projected use for one.

There are a lot of places where they get in the way, can't be used easily or are not allowed. Tourist spots, museums, churches, narrow sidewalks, mines, caves, etc. come to mind. Adding a tripod to your camera bag can be rather cumbersome to carry around all day when you are exploring a city on foot.
By carrying around a tripod, you are also advertising the fact that you have expensive camera equipment which is not to be recommended in some areas.

I find a tripod is great for formal portraiture of several individuals that need to be similar but I find that it would slow me down considerably on a model shoot. Product shoots, macro and creative work also lend themselves to tripods. Moonlight over the lake shots and dawn shots benefit from a tripod as well.

Although I have 3 tripods at the moment, I don't use them nearly as much as I expected to, when I first bought them. With high ISOs, off camera flash, battery powered camping type lighting or even high beam headlights are being used to light up large areas and shoot with a handheld camera.

Tegan