a/b - phpVMS doesn't use any timezones. It's all done as whatever timezone you chose and remain consistent. For instance, if you want to list all times as local to that airport, you can do that. If you want to list everything in GMT, you can do that as well. As long as you remain consistent. Flight durations also vary depending on aircraft, and maybe your airline policy is duration is gate to gate, not runway to runway.
c - You can change in the config to not use a currency (since it is just a display), and you can make a note that the currencies listed are local
d - this has come up before, if I get time to implement them, I will. But that is also why the CSV import exists, so you can do that a bit more easily