Huh, I have carefully reread all your requirements (a lot, ha?
), trying to give you my modest experience support.....
1) Bugs burning power: handheld lasers do not have sufficient power to do what you want, nor within few inches and less at 3 - 7 ft distances. You can make a bug flying away, but not incinerating it.
2) With the exception of very low output power (let me say, from 0 to 30mW max, and someone may disagree with this last value) you'll have always the need to wear safety goggles when looking at the laser point at short distances, like those that you can generally have pointing the laser inside a room. Due to the different wave lengths, you'll need a safety goggle for green and another for red laser. For some cheap goggles you can give a look at:
http://dragonlasers.com/home.php?cat=296
3) Laser beams may have different diameter, according to the diode and the group of crystal/lenses used: the green lasers that a lot of good guys have suggested you are not focusable (with the exception of the use of a beam expander, in the cases it has been foreseen) and their beam diameter is small, about 1.2 mm, and their divergence (always generally speaking) goes around 1.2 mRad. This is good because there is no need to focus for burning purposes that can be simply achieved according to the laser power.
The DX200 red laser has a greater diameter (about 5 mm.) but it is focusable: this means that you must screw/unscrew the front head to focus the red point on the object you want to point at, especially for burning purposes, as smaller is the laser dot, more power is concentrated in it.
4) No special IR protection is needed, as the green lasers produced by good factories as Nova, etc. have already the IR filters installed, while red laser do not produce IR. But you need to protect your eyes against the burning power of the laser, as said before: nearer to you is the laser point and more careful you must be. Pay particular attention to reflective surfaces (mirrors, metals, glass, etc.), because the reflected laser beam is dangerous as the direct one.
5) Concerning visibility, the green laser beams are surely much more visible than the red, and the distance goes according to the power of the laser: as already suggested by other Forum Members, the laser power choice is a mix between visibility and burning characteristics.
So, in case of the visibility single requirement, a 75 - 95 mW can be sufficient, but the burning power..... :-/
The general statement of (let me say) all Forum member is: "give me more power!" Obviously the single person limit is....money!
So, to conclude for your green laser choice, Nova X serie is surely good, and for the power, check your pocket!
