1. Some CFLs or LED grow bars (depends on you budget). Check out the LED thread under advanced techniques.
2. Check out carbon filters, but for just two plants this shouldn't be a huge issue. You should be able to just circulate the air from your room, as long as it gets fresh air from somewhere.
3. No need for shielding if using CFLs, and definitely no need with LEDs.
4. No idea.