You can find info on supported screen resolutions for external monitors connected to Surface at https://support.microsoft.com/en-us/surface/supported-external-display-resolution-and-refresh-rates-for-surface-7ecabde9-4b06-4aa0-95e3-b64ddd3b38a2
As for what resolutions are used for different things, that is a personal preference coupled with the limits if the video card and PC connected to the monitor, there aren't any real hard and fast rules. Since you posted under the Surface Go tag, the max resolution is 3840 x 2160.