Re: Minimal Impact
Everyone who has used Find My at least once.
Go to Find My... oh, wait, you need to use a different device. Log into any computer (including other phones, tablets, whatever) which has an Internet connection. Go to icloud.com. Log in. It would be best if you used a device which you have previously logged into iCloud to do this, such as a computer used to back up the original, now stolen, device. You do back up, don't you?
Once in iCloud, go to Find My. Click on the stolen device. Find My should show its location, if it's on. Even if it's off, Find My should show several large buttons, the first three of which are 'Play Sound', which plays a loud annoying sound on the device to help you find it, 'Directions', which gives directions to the last known location of the device, and 'Lost iPhone/iPad/whatever' which turns on the lost feature. And disables the device.
If you have logged into the computer you're using for iCloud before, you will have access to Keychain, which will have the passwords.
If you have never logged into iCloud on that computer before, you will have to put more effort into it, but it can be done. If you don't have another computer available, you're screwed.
Personally, I have logged into iCloud on multiple personal desktop and laptop machines and several office and school desktops; I wanted access to my iCloud files. This means that I can use any of them for Find My should I wish, the Apple devices among them will automatically get the 'trust me' six-digit codes, the Windows devices will take more effort. Linux won't work; at least I've never been able to get the 'trust me' code on a Linux system, if anyone else can I would appreciate finding out how you did that.