You can train certain parts of your body, what you can't do is spot reduce. So if you want nice strong legs so you can run, walk and kick better, yes you can train them. If you want nice slender thighs so you can wear a purple skintight mini, then no, only diet and overall cardio will sort that out!
The ball is fabulous for abs and for doing dumbell type exercises, and for overall core training. There are stacks of resources out there to help, like dvd's, books and websites. This one is one a lot of us refer to over and over again
http://www.stumptuous.com/cms/index.php
What you're doing already is great and you are managing your time really well. What your proposing, doing strength training every other day, is fabulous, as it's what I do!!!
The forums get busier at night (when I am asleep - I'm in England!)