My dad told me the following. You can downshift when you need to but dont do it every single time. He taught me to just drive on the gear that you are in and just break without downshifting till the point where your RPM drops down very low under 1000 and you feel like your car is almost stalling, and than to switch into neutral. In other words brake and stay in the gear and dont downshift. He drove stick shift cars for like 30 years already and I trust him. He said that downshifting is not really necessary but it wont hurt the car if you know what you are doing. He also said and I heard many other people say the same thing that back in Russian they used to downshift during snow on their rear wheel drive cars so that the cars stop like on icy roads. Also switching gears without clutch is not a problem and possible on any car. My dad did it on my car but I personally never did it. I hope my post was useful and not boring.