For such an object, I would recommend using i3pro. The i3lite product is designed for simple, not very large installations.

The panels synchronize the project over the Internet.

And each panel connects to the equipment independently. Therefore, if you have 1-3 panels, then this works quite well, but many equipment does not allow the simultaneous connection of many devices, and in this case, using the server helps: only the server is connected to the equipment, and all panels receive information from the server.

Yes, it is. The license does not limit the number of panels on the object, but the interface on all panels will be the same (style, widgets and titles)

Sorry, but there are no plans yet. Perhaps it will appear in other products of the company.

iRidium server does not support virtual servers. This is due to the licensing system.

Hello

we have documentation: https://dev.iridi.com/SIP-telephony

At the bottom of the page there are examples of projects for working with different intercoms.

To work with an intercom and i3pro, you need a SIP compatible server and that's it.

Они сохраняются автоматически (не пропадают после перезагрузки) и перетираются только при загрузке новой версии проекта. Уточните подробнее условия возникновения ошибки, версию и платформу сервера, если есть возможность, приложите проект, на котором это повторяется.

P.S. И лучше создать отдельный тикет в службу техподдержки.