A: Thanks for your questions, answers below:

1 - Custom domain is available only if I deploy at least in your Small plan, right? 10$/month

If you you would like to run on your domain yes you need one of our deployment plans

2 - When deployed, I still have only 5 users that can access it or can I create, for example, a recipe website and use it for several users?

On the app.buzzycompany.com you're restricted to 5 users, as it's a multi-tennant server and don't want folk. On your own deployment Small/Med/Large there's no restriction on the number of users

3 - Can I integrate it with Airtable?

yes, Buzzy can pull data out of REST APIs. Note with Buzzy we include the database and you get your own Database cluster for you deployment, so Airtable may not be required. Try deploy the REcipme app https://www.figma.com/community/file/1029611274243484751 and look at the backend CMS. It pulls data from a REST API... which could have been Airtable or any other source.

4 - Do you consider removing the "Powered by Buzzy" from the small plan for lifetime users? And can you also share a screen on how it looks like?

it's currently not on there today. We need to add the "powered by Buzzy" in and just have not got around to it, so be quick ;-)

Thanks!