No. Some plans, especially cheap unlimited ones, restrict or forbid it. Read the hotspot row in the plan's spec table before buying.

The laptop treats it as ordinary internet and pulls system updates and cloud sync. Mark the connection as a metered network.

Usually five to ten depending on the handset, though speed is divided by whoever is actually using it.

No. Count only those who will actually rely on this hotspot's data. Anyone with a separate plan should not be folded into the sharing phone's load, since they already use their own. If you are not sure who in the group already carries a plan, ask before the trip rather than guessing while running this calculation.

Noticeably faster, though the exact rate varies by phone model and how many devices connect at once. This tool does not calculate battery at all — treat carrying a power bank as the default whenever a phone is doing the sharing.

Check the plan's own spec page, on the hotspot row specifically. Many unlimited plans set a separate hotspot allowance apart from data used on the phone itself. This tool has no way to know any one plan's specific terms.

It depends on the technical limit of that model and operating system, not a number this tool sets. Check that model's own spec sheet directly if the group is fairly large.

Consider splitting into two hotspots, with a second person buying a separate plan to share from, rather than leaving everyone dependent on one phone and one plan. This also lowers the risk from a battery running out mid-day, since the other phone can pick up the slack if one has trouble.