I'm trying to understand the instructions in the manual for the 2014 (US) Mirage, but the steps I've bolded/underlined doesn't seem clear to me, can anyone clarify (my comments/questions in italic & blue)?

For F.A.S.T.-key programming, follow the procedures below.

1. Open the driver’s door.
NOTE: Keep the driver’s door open until F.A.S.T.-key programming is finished. Do not open or close other doors.

2. While carrying the first valid F.A.S.T.-key, put the operation mode in ON. (Perform the following procedure within 30 seconds.)

3. Insert the new F.A.S.T.-key into the key slot.

4. With the first valid F.A.S.T.-key, press the UNLOCK button for 4 to 10 seconds and press the LOCK button during this time. (does this mean to press & HOLD the unlock button and press the lock button while holding down the unlock button?)

5. Release in sequence the LOCK and UNLOCK buttons within 10 seconds of pressing the LOCK button in step 4. (Perform the following procedure within 30 seconds.) (what does it mean to "release in sequence"?)

6. With the second valid F.A.S.T.-key, press the UNLOCK button for 4 to 10 seconds and press the LOCK button during this time.

7. Release in sequence the LOCK and UNLOCK buttons within 10 seconds of pressing the LOCK button in step 6. The immobilizer warning light will blink.

When registration of ID code is complete, the buzzer will sound 3 times and the immobilizer indicator will come on for 30 seconds]. (what buzzer?) If an error occurs, F.A.S.T.-key programming will be terminated and the buzzer will sound for 3 seconds.
NOTE: F.A.S.T.-key programming will be terminated if the operation mode is put in OFF before the immobilizer warning light starts blinking.

8. If you wish to register another F.A.S.T.-key, repeat the process from step 1 after the operation mode is put in OFF.
NOTE: The immobilizer display will go off immediately if the operation mode is put in OFF. It is not possible to register a F.A.S.T.-key if the immobilizer warning light goes off during the procedure.