Looking at the footage it's striking how swiftly the shooting happens. The way the DA is presenting his case, you would get the impression Brooks fired the taser and Rolfe shot him 10 seconds later. If you look at the footage though, you can see that Brooks fires the taser at Rolfe at 23:22:48. You can clearly see the flash and can hear the discharge. Rolfe then fires his first shot at 23:22:49. I looked at the footage frames and Rolfe draws his weapon while Brooks' arm is still extended, pointing the taser towards Rolfe. Rolfe fires his first shot while Brooks in the process of lowering his arm, still holding the taser. We're literally talking millisecond events here.
With regards to the alleged kick, at 23:22:58 Rolfe appears to be making a sudden motion with his leg. His leg is obscured by a car though. The exact nature of the motion can not be determined based on this footage.
With regards to the charge of not giving first aid in a timely matter, it's true that there are roughly two minutes between the Brooks collapsing (at 23:22:50) and the start of first aid (23:25:00). Though the DA seems to imply Rolfe and Brosnan just stood around for two minutes, this is not the case. Rolfe reaches Brooks at 23:22:54. The first minute Brosnan and Rolfe appear to be securing the scene. At 23:23:55 Rolfe runs back to the police car, opening the trunk. He rummages around and appears to be putting on gloves (I assume these are medical gloves), occasionally talking into what appears to be the mobile phone attached to his shoulder. At 23:24:52 he runs back with the medical aid bag. At 23:25:00 he kneels down next to Brooks and begins giving him first aid, helped by Brosnan. All in all I can't say that the officers didn't start giving medical aid in a timely manner.