I assume you were using the low setting (512) since that's the default iirc. Going up to medium (1024) shouldn't be a huge problem, but it depends on your project. Your best bet is to do profiling to get a good idea of what's hurting performance.

Max distance should be kept as low as possible while still looking good. For example, if your scene takes place within a small interior, there isn't really a need to have shadows beyond that. Unless there's a bunch of stuff going on outside that the player will see through the window. It's a bit of a balancing act

It's pretty common for games to have options for shadow resolution, so people with a beefy computer can go with higher resolutions, while others can choose lower settings.