I use ING Direct for my cash savings and have found their affiliate Sharebuilder good for trading. Plus the integration between the savings account and the trading side helps if I want to move quickly on something. $9.95 per trade, with the usual options for dividend reinvestment, etc. I track performance by manually uploading trades into profiles in Google Finance, though tracking dividends in Google Finance is a fracking mess and I don't do it.
My buying/selling cycle is pretty long. Right now I'm focused on accumulating long-term investments, so I sell rarely. What I have sold has usually been after 8-12 months.
My goals are also modest at this point; now that I've saved enough cash for emergencies, I'm focused on earning a return that's higher than my savings account (without touching my emergency savings fund).