it's possibly a bug either in gameplay or in Cpedia.
I do not know how to make the damned adds to be visible on sreenshots, but you can test in WB or just notice it when playing - combats odds involving gunships do consider first strikes, and, moreover, they depend on first strikes.
Say, a gunship attacking a DIV Mobile Artillery has ~11% odds, while, against an unpromoted one, it woukd have ~32.
Is there a patch ti fix either Cpedia or game mechanics?

EDIT: Ah, btw, i have BtS3.17. I do not know if any patches are applied, but in my version you can found corps under Merc, so i guess i have the Unoficial patch as well.

You can found corps under Merc.
You can not found corps under state property.

The unofficial patch fixes a wide range of issues. You can always drop them a line and let them know the bug is present. they will then see if they will fix it or not. Other than the unofficial patch - which is not hard to find - I do not think there are patches around adressing this issue.

Do gunships claim to ignore FS? I know cavalry don't by default. Flanking II provides FS immunity for any unit that has it though.

Only Horse Archers and Knights get immunity to First Strikes.

Gunships have the following bonuses (and penalties):

Cannot capture enemy cities
Doesn't receive defensive bonuses
Flies over terrain
Can withdraw from combat (25% chance)
+100% vs. Armored Units
Flank attack vs. Cannons, Artillery, and Mobile Artillery

The only way for Gunships to get immunity to First Strikes is to promote it to Flanking II as stated above.

Cuirassiers?

Cuirassiers?

They have FS immunity by default. A lot of people forget about them for some reason though, even though they're the first dominating renaissance unit!

Makes perfect sense - a longbow man ought to be able to get his arrows in before the Gunship closes to hellfire missile range.

Makes perfect sense - a longbow man ought to be able to get his arrows in before the Gunship closes to hellfire missile range.

Wow, that wasn't sarcastic at all. :-D