The "in battery/out of battery" reloading he is referring to is the condition of the slide on the pistol. In battery refers to the slide being fully forward, while out of battery is the slide being rearward(even slightly rearward). Think of it as an artillery piece.

Remember that the things you do while practicing become a part of your muscle memory. Try to not practice techniques that require fine motor skills, as when/if you go into condition red, you will lose control over these finely tuned muscles.

You may also want to find a range or individual that has reactive targets, such as pepper poppers, that you can integrate into your shooting regimen. Poppers are good because they teach you to keep firing until the target is down, a good skill to acquire for combat. Good drills are ones that will prepare you for likely sitions that you may face on the streets. Multiple targets, close/far, varying threats (gun vs knife) etc. Work gradually into any regimen, and slowly progress as you are able to do more and more.