Is there a way to scale my figure so that it has the exact weight and height that I want to design?

Uh oh, there's that word again! ;=[

Load your figure. Select its body. Look over the parameter dials for Scale. Default is set at 100%. You may increase or decrease that scale. You can scale specific parts. You can make legs shorter by setting YScale on the thighs and shins down to 90%, for example. Make them longer by going up to a YScale up to 110%. Just changing the YScale will either make them shorter but thicker, or longer but leaner (relatively speaking). Increasing the XScale on the torso a little bit can have the visual effect of adding pounds. Decreasing the YScale does the same thing, and makes the person shorter. For anything more, you need to use morph targets (downloaded or bought), or make your own in Poser using magnets.

Thanks so much for the information! It will help me out a lot. So, let's say I wanted the figure to be 150 lbs, there's no way I can just plot that in somewhere? Would I just have to estimate the body size?

Considering 150 lbs looks different on every person... hehe If you have V3, she also has body morphs to change her 'weight'. Some of the 'Heavy' morphs aren't particularly realistic, but you can use some of the full body morphs with negative values or in combination to get the affect you want. The only real problem is if you do, conforming clothes are a misery to fit. Hooray for dynamic cloth. -.-

Don't be afraid to guess using your eye. But, if you really need conformation that you're creating something that matches a certain set of statistics, go to an online model registry. (I don't mean model as in 3D graphic object, I mean model as in flesh-and-bones men and women who model clothes and such.) Look up some models, look at their pictures, and check their stats.

Hooray! Thanks so much guys! Success!