Strongpoints

[triangular_cube]

My take on this one is that the strongpoint defenders get an exclusive first fire in assault combat before their comrades in the same hex (outside the strongpoint) get to fire simultaneously with what may be left of the assaulting force.

No, that is not how is. Rule 12.43, halfway through the first paragraph says:

If the hex contains defending units that receive first fire and units which do not, the defending player may choose to take First Fire with only the units able to first fire (the others don't fire), OR use all his units and resolve the assault simultaneously with the attacker.

So if there is a strongpoint in a hex with other units, not dug in or entrenched, the strongpoint may take first fire alone and there is no other defensive fire, or it may join the other units in simultaneous defensive fire. Regardless, the attackers are not subject to 2 rounds of defensive fire.

Its certainly strange that I'm not the one standing by the literal interpretation of the rules for once 

Its a very valid reading of the rules to play it that way.