For the Airport Express Traveller Pass, HKD300 (2 way Airport Express). I'm staying in hong kong for 5 days, if i use 1st-way during 1st day from Airport, will i be able to use the 2nd way at the 5th day when i leave for airport?? The HKD300 includes a HKD50 deposit, rite?

The 3 days consecutive pass for MTR, it is effective for 72hrs or count the days in which is it used. Because i'll be arriving at the airport at 5.35pm, so 3 days is until 5.35pm at the 3rd day, or, one-day ends at 00:00 hrs??

If 2-way Airport Express Traveller pass is not convenient for me, and i would like to purchase the 1-way Airpot Traveller's Pass (HKD220), can i buy it at any MTR station? The Airport Express 1-way, can also be used on the 5th day if i start using my MTR unlimited pass on the 1,2 and 3rd day??