SureFire M952V LED WeaponLight for Rifles and SMGs — White and IR Output

It's worth pointing out that lights are for observation and target identification only, and lasers are for aiming without needing to use the sights - two completely different purposes.

The light is a fairly important piece of equipment for home defense, because identifying targets is critical to shooting accurately in the dark (e.g. silhouetting the front sight post), and avoiding shooting friendlies (e.g. teenager sneaking in late).  Put one on every long gun, in a location that can be activated "momentarily", with your hands in position on your gun (e.g. on the rail).  You should also have a hand-held light nearby, that can be used to search for targets without having to point the weapon at them.

The use of the light is brief and intermittent, to search for or identify a target for shooting.  The light is momentarily turned on to search or identify, then turned off again.  You're not just walking around with the light on, giving away your position. A good example that most people may be familiar with is in the ending interior gunfight in the movie Act of Valor - there are some very clear illustrations of proper light and laser manipulation, performed by real SEALs of course.

I'm not convinced there is a good argument for intentionally not having a light. It's there to use if and when you need it, at which time it is a combat multiplier. For example, you may have been able to stop a criminal without shooting, and need to keep them subdued under armed observation until law enforcement arrives - doing this in the dark would be difficult, and could allow them to present a weapon unnoticed. Modern tactical lights are very bright, very lightweight, and have come down dramatically in price.

Lasers are far less necessary or useful, because there are not a lot of anticipated situations or positions within a home where you would be unable to use the sights effectively.  One advantage of a laser is that, if you are using unmagnified combat optics (e.g. red dot), you can use the laser as a backup that will appear very intuitively similar to the normal sight (e.g. laser looks like red dot through the sight window).

On the point of weapon selection, all pistols are underpowered and too low in capacity.  They are weapons of compromise for the sake of portability.  Home defense places no restrictions on portability, so you are much better served by the combat power of a carbine.  The interior dimensions of American homes are not so constrictive as to make maneuvering with a 16"-barreled carbine unfavorable.  In our testing, the average shooter tends to be about 10x more accurate with a carbine than a pistol, so the accuracy benefits are also highly desirable.

As suggested previously, training for these types of Close Quarters Combat (CQC) scenarios is critical to success. Seek out competent instruction, and visit a simulator or range that uses Simunitions.  Decide for yourself what equipment you need to fulfill your mission essential tasks.