Attendance not get recored in attendance sheet

ERPNext
1
  1. If employee mark chek in check out for the day then currently attendance not get recorded in attenance sheet.

we have created shift type and assigned to the employee.

  1. If we import bulk attendance data and also import employee checkin data through import tool then how can we link both data.

  2. Is there any auto schedular for employee check in and check out to update auto attendance mark in system.

  3. as per check in check out system should calculate the overtime based on shift type for working hourse and should add on over time for the month for payroll.