I'm by no means an expert but I will try and answer two of your problems.
(1) You may want to set up a new table called Locations so you can create a relationship between Airports and Locations using the Airports primary key in an Airport field (foreign key) in the Locations table. You may then want to read this post:
(3) You have a few options here. I'm not too sure if you just want to hide the Jet_Photos_ID field or the whole right hand side of your screenshot. If the latter is the case maybe investigate using tabs and hide layout elements on a specific tab.
If you simply just want to hide the ID field then you can use conditional formating and set the field contents to the background colour. The problem with this is that you will still be able to click into the field space or tab to it using the tab button. You can though, use Script Triggers to 'prevent entry' to the field, or use custom privilige sets to lock down that field conditionally. The latter is more secure but much more work. The former is quite crude, but simple. Use a script trigger that when OnObjectEnter runs a script that checks if 'Accepted' and if not, go to next field.
Thanks so much for that, I now have the locations list (and a few others) working, along with the conditional formatting (just hiding it is all I needed). The main thing I need now is to set up the buttons to open specific files. Is there a way I set up a formula for that to open a local address that is dependent on the contents of the fields?
I will be playing around over the coming days, adding new features so I'm sure I'll have more questions soon!