Enable modules on nginx and ubuntu

I have a server with nginx installed. I'd like to enable modules (specifically ngx_http_map_module). Ok questions:

1) How can I check if the module is installed or not? 2) What is the workflow for installing the module? The only way is to stop nginx, remove it and recompile with the new module? 3) Stopping nginx isn't an option as there is a live website already. Any other options for adding modules?

The http_map_module is compiled/enabled by default

So you shouldn't have any problems using it. Add the necessary config to your files then reload nginx - this will cause it to check your config first before reloading and it'll let you know of any errors without taking your site offline.