Hi!
- The altitudes have to be within a certain range. If the ceiling would be very high, then departures will likely incorrectly 'divert' at the boundary instead of flying through the ceiling. Looks like in your case the ceiling was lowered to FL140 automatically. Perhaps some limits could be adjusted, however more divergent values than those used in built-in airports may skew the game mechanics.
- The 'above' property is just the highest altitude you can select for departures only, being somewhere above the 'ceiling' value. For example at EHAM it is set at FL130. I'll try to improve the sketchy explanations :)