How do I change the rate modules output to "# of users like this"?
I haven't used the module. But looking at the code, you essentially need to override the preprocess function in the module which is used to generate the string.

Open rate.module in an editor and search for the text string that you are looking to change. In this case, this string would be something like "have voted", which should lead you to the function named rate_preprocess_rate_template_thumbs_up(). This is the function that you should look to override. You can see that the strings are added as part of two format_plural calls and should be straightforward to amend in the override function.

You can perform the override either from a custom module or from your theme's template.php file. Since the module is using a preprocess function to make its changes, I recommend using a process function (note the difference in name) when you override it. There should be plenty of documentation and examples available on drupal.org and drupalSE to aid you if you are unfamiliar with overriding.