KlarSnow

You should go look up the principles behind TDOA, TDOA is Time difference of Arrival, not angular measurements. Each station is receiving and synchronizing the time of arrival of a particular signal and using that time sync to generate a location. With 1 station all you get is a range, thus a circle around your aircraft. 2 stations would give you a pair of potential locations, and 3 stations gives you a very accurate location.
This does not work the same way as angle based triangulation systems.
 
Each intersection of a circle is the potential location of the target, only where all three intersect is the true location.

This is accurate and not a bug. If there is no active sensor providing the height above target then the CDIP calculation pulls the current designation or closest steerpoint elevation and uses that.
Suite 4 as implemented does not have DTED tied into its bombing calculations.
Your only sources right now for height above target are SYS, wwhich isaircraft barometric or GPS corrected altitude compared to the steerpoint elevation. Or LAS which is the target pod latched to the CDIP reticle with the laser firing. The other parts of the height above target hierarchy: Air to ground radar ranging, Radar altimeter, HRM and Passive are not implemented. of those, only Radar altimeter an Air to ground radar ranging would help with CDIP bombing.

designating an offset designates the target. Offsets are not additional targets they are offsets. When you have TGT cursor function and designate with an offset in PB17, it will designate the target point associated with the offset at the bearing and range from the offset that was saved.
The behavior you are seeing is correct.

No, its automatic and part of the pods safety features so it doesn't damage itself.
SNIPER has no limitation like this, so whenever it arrives you will be able to use it at whatever altitude you desire.

Here 
1
l
2

3

4

5

Tacview HUD view of the missile in question during the time period in question. It is falling, its pitch angle is decreasing, so it MUST accelerate.

80 seconds for both versions of the AMRAAM