Can I swap my fixie frame and still keep all my old components?
It is possible, but not likely economically a good move, especially if you're not doing the labor to swap the bike parts yourself (assuming you own the tool to remove the bottom bracket and what not). The bike is a relatively cheap one (~300 dollars), and you're likely to come out better financially by selling the bike and buying a larger one (which may have some slightly different components spec'd on it, such as different crank arm lengths). 

50 cm -> 58 cm is quite a large jump as well, but that is a peripheral point.