Is it sufficient to use Lucee in bulit Tomcat server for production apps? What are pros and cons? Is there any need to use IIS or will Tomcat do the job ?

This is kind of apples to oranges, iis is not a servlet container. Front end termination can be handled by iis or nginx or you can use something like tomcat or undertow (since you're running one of the two anyway, most likely). We prefer to use a dedicated front end web server but I know there are folks just using commandbox/undertow

Almost all the production apps I use use Tomcat. We deploy via Docker, but the setup is the same. Apache -> Tomcat -> Lucee

Right but you have apache in front. I think the question was whether you can just use tomcat. Which you can but idk that it saves you much trouble

You absolutely can. BUT remember every asset will be run through Tomcat (images, css, etc). That can add additional load to the server and make it less performant in most cases. That being said, there is nothing /technically/ wrong with doing it that way.