Most people change into whatever is nearest. The useful version is something you can get into standing up, wear for hours without thinking about it, and that does something other than cushion.
Yes. That's actually the most useful window for them. But at first, wear them 10 to 15 minutes at a time for the first few days, then wear them as long as they feel good.
No, and be careful with anyone who tells you otherwise. Numbness on the bike is usually about shoe fit, cleat position, or pressure at the ball of the foot, and the fix is a bike fitter or a podiatrist. Persistent numbness is not something to train through.
Yes. Plenty of people do. You finish, you want out of your race shoes asap, but also want to keep your feet switched on, and these are the fastest way to do that.
Different tools. Boots run for twenty or thirty minutes while you sit still. These do something small but vital across hours while you get on with your day.
Yes. The outsole has grippy cut-out hexagon patterns and grooves that channel water away, which is the exact thing you need on a wet tile floor.
