Tax questions about selling stock/mutual funds

[mo42nyy]

If I buy 100 shares of stock A in Janurary 2007 at 5 dollars a share and buy another 100 shares of the same stock in July 2007 at 3 dollars a share and then sell 100 shares of the stock a year later at 10 dollars a share how would i be taxed on it?

Also
I know you can sell stock/funds at a loss for tax purposes as long as you dont buy the same stock/fund within a month of selling it. Should you automatically do that at the end of the year if your stock is down for tax purposes?