Installation on my web server: classic or third level domain?

Hello everybody,
before write this post I have already read many documents, post, forums, etc, without find any solution to my problems.

I hope that somebody can help me.

I have a Ubuntu server used to host many web application (web portal, cms, etc) for my job and for my clients.

I have tested Jitsi using the API, but I had some issue regarding use of microphone and video, maybe cause of the partial setting that I can manage, being the application on Jitsi server (https://meet.jit.si/).

So, I decided to install Jitsi on my web server.

And now my questions:

  1. I suppose that installing Jitsi on my server, it works like https://meet.jit.si/ it’s correct?

  2. If above is “yes”, I suppose that I can use API including my domain, with following command:
    const domain = ‘my_domain’;

It’s correct?

  1. My goal is to use jitsi integrated in my website, using the API (linked to my domain), and don’t have a website where people can go there, and use it as they want (like https://meet.jit.si/). There is a way to disable the front-end, avoiding that people can start videoconference privately?

  2. and now, maybe the most important question that it is stopping me to start. The “domain”!. Maybe my question is stupid, but I want do it anyway. Everywhere I read that for installation I have to use a domain like “jitsimeet.mydomain.com”. This means that must have a third level domain active? Or I can use as domain simply “mydomain.com” ?

I don’t have any third level domain, right now, but obviously can activate a new one.

Thank you everyone who can help me.

BR