Ye It would depend how detailed it is and ideally it could do with downloading the app to a pc at the end of the day incase of a computer crash.
A few hundred, the trouble round here is there's quite a few company's doing it and generally if customers wanted it doing they were already having it done so I diversified into different areas
The main problem you may have is if you do widow cleaning now on set weeks you may have to change it for around the bins as their emptied on one day and particular times. So you can only clean them on the one day and after their emptied which for some can be after 4pm