5W will surely be too much for lightining, get a red or yellow one, as white are usually brighter, but as long as is far away and as long as you check your pacman eyes(or pupils), they should not be too little when the light is on. This way you ensure that he sees fine and the light is not to bright.
For the CHE i'm pretty sure 25w is not enought for a 10gallon, 40W if you're installing it outside throught the grid it'll not be enough too. I would get at least a 60w with a thermostat. Givemme some news when you have some.