Is there any way possible to display to all users of a faction who install the script to see the current status of all players of the faction who have bank access, whether they are online/offline, jailed/hospitalised or currently travelling and if they are travelling back to torn, display flight time left.
Current status is the only thing you can get via faction API. Filtering by banker is something you will have to program in (no way to determine if someone is a banker or not: either this can be predetermined, or updated regularly or something similar).
Flight time is not available from a different perspective: only the user flying can see the exact time. Again, you would have to program in a way to estimate the time left (there are a couple different methods for doing so).