1 - Email blast! And it depends on the type of company. If you are a property management company with lots of employees you're right a lot of people won't use it. Then UpKeep becomes a more internally facing tool for admins to enter in requests and dispatch jobs out. BUT if you are a maintenance heavy company (industrial, manufacturing, etc) you are used to submitting work requests and tickets in every single day.
1b - Yes! So basically the requester normally has the most information. If they can take a picture and send it in with the work order, it is soooo much more descriptive and helpful to the admin user. They can also call it in, and UpKeep works in both ways. But it adds additional overhead to the admin users to be manning the phones at all times.
At the end of the day, UpKeep works in both scenarios and it really depends on the workflow of the company! :)