I’ve had good luck with these. They come in various weight ratings. You don’t need to find a stud. And they only leave two very small holes to patch when removed.

Probably not.

I use tapcon screws.

You need to use a hammer make a hole first.

You won’t have much luck trying to drive a brad into a metal stud while trying to hang a painting or a mirror, but I’ve had no real trouble driving screws through the studs, and these are plenty sturdy and strong, even for disability grab bars. The crucial factor is using a decent electric drill for driving the screws and putting your weight behind it. You won’t have any success just holding the drill and pushing. Use a stool or ladder and hold the drill with both hands and sort of lean against it with your chest. I recommend that after finding the center of the the steel stud using a stud finder, you drill a hole with a 1/16” drill bit or hammer in a small nail to be sure you are on the stud and not on empty space beside the stud. If you are trying to install, say, grab bars or wire shelving or cabinets and the studs aren’t in the right place, one technique is to install a wood strip (whether 1x2” or 1x4” or 1x6” as long as you need that is screwed into the studs where possible, then screw or nail your brackets to that wood. This is especially useful when you need to hang things in your garage.

Interior walls are generally metal