The state before you start, the pipes before the boarding goes on, the extra work agreed on site and the result. Every photo carries the date, the time and the place, an independent service timestamps the file, and on Plus the report carries your logo.

The pipes behind the plasterboard, the insulation under the floor. When the client asks later, the photos are all there is.
Agreed on site, disputed at the invoice. A photo with the time puts it on the record.
A crack in the tiles, a scratch on the floor. Without a before, it is your word against theirs.
The Work that gets closed up template in the app asks for the space, the pipework in detail and the connection points before anything is covered. Progress keeps the stages in between.
On Plus the report carries your logo. If you want the client to sign on site, that works on Business, with a checklist of your own in which the customer signs at the end.
The space, the existing damage, and the meter if there is one.
The pipework and the connections, then close the file so it is timestamped on that day.
With your logo on Plus, next to the invoice or at handover. The client checks it in the browser.
They open the file in the browser, with no account and nothing to install: the work before it was covered, with the time from an independent service.

No. They open the file or the link in a browser. Only the person taking the photos needs the app, and Basis is free for one file a month.
Yes, with a Business bundle: orders, your own checklists and a dashboard to follow the work.
In a checklist with a signature step, yes, and the signature goes into the file. Of the built-in checklists only Key handover has that step; Work that gets closed up, Completion and Progress do not. On Business you switch on ‘The customer signs at the end’ in a checklist of your own, for example for the handover.
The date on an ordinary photo comes from the phone and can be changed afterwards. Here the time that counts comes from an independent service, and the page shows the window between the photo and the stamp.
Basis is free: one file a month. Plus gives you five and your logo on the report.