RE: rail to rail - opamps are all a little different from one another, and none of the behave exactly like an "ideal" opamp. and there are a number of different ways in which they stray from this "ideal" behaviour. one of these has to do with how close a signal can get to the powersupply, both for signals being applied to the input pins, and the signal coming out of the output. the TL082 is pretty bad about this, it can only get within ~3V of the output rail, on both the bottom and top rail. The LM358 is better, it can accept inputs all the way down to the bottom rail, and apply outputs all the way down to the bottom rail, but can only go as high as (Vcc - 2V) at the input and (Vcc - 1V) output. so if you were to run it off 0V and 5V rails, you could only get an output swing of 0V to 4V. so its almost rail-to-rail, but not quite.
i usually like to reccomend the TLV2372 for generic rail-to-rail circuits. its a little more expensive, and not available at the corner electronics store, but acts more like an "ideal" opamp. the MCP602 is a good opamp as well, but it can not accept inputs all the way to the positive rail. the MCP6002 is also a good choice, as it is very inexpensive and has full rail-to-rail inputs and outputs (RRIO), but i only hesitate to reccomend them because they run off 6V max. so if you want to do a 9V battery circuit at somepoint and not use a voltage regulator, it will fry the amplifier. so i generally keep a stash of TL082's and TLV2372's, and use the latter when i need rail to rail.