A question from a Noob

So I purchased an atem mini pro iso to help with my videoing myself playing drum videos. I have 3 cameras plugged into the atem. I see all three shots on the screen. When I hit record does the mini pro turn all three cameras on at the same time for me? Also, do I need to download davinci resolve for my desktop. I didn't see a disk in the box for davinci. I have had this unit for a couple months but didn't have all the lights and other gear I needed to do my videos right. So if while recording I make a mistake and have to start recording all over, I assume if I hit stop on the atem and then record again it creates another folder? I also just need to know what buttons need to be pushed to record music live. I am not streaming or swithing cameras manually because I am drumming.

Thank you for your grace and kindness in answer these questions. I learn better by having someone show me how to do things and I haven't found any vids that walk you through doing exactly what you need to do. Of the bottom three buttons on the right do I just hit auto or does it matter at all which button is lit. I thought I just hit record and would be golden. A friend who has this device but lives in another state told me I had to turn my cameras on but when I do that and then hit record on the atem nothing happens.