My understanding of reflex sights is that they are designed so you don't need perfect alignment for them to function. Plus, many of the reflex sights are always on, so you don't need to worry about turning them on.
1) A reflex sight, holo sight, or red dot sight all work on the presumption that you don't have to be in direct alignment with the sight to the target in order to hit what you're aiming at. If you're not perfectly aligned, the dot's location inside the scope will change - but the dot will still be between you and your target. As long as you can see the dot, you can hit the target.
Personally I haven't tried it on a pistol, but I can't see how it would be harder to pick up on a reflex sight than it is on irons.
2) Trijicon RMR and Burris Fastfire can last over a year. Leupold Deltapoint I believe about 4 months in always on. There are also reflex sights that use tritium and fiber optics, which means no need for batteries (just replace the tritium lamp every 15 years or so). Always-on optics are great for a self defense gun.