1. It depends on the school.
2. They should provide information on your achievements in the workplace, ability to lead, work in teams, etc.
3. It is possible
4. Schools know that LOR writers are busy people so they will be reasonable in their attempts to reach that person
5. The schools want to verify that the LOR writer actually knows the student and is aware of the contents of the letter
"The UCLA FEMBA program uses Kroll Background America to verify all admitted students who choose to enroll. All offers of admission are contingent upon successful verification of recommendations and employment information; applicants who choose to accept their conditional offer of admission must authorize the information verification and are charged an additional fee by Kroll Background America to conduct the information verification."