tank you for the quick response!
What I tried to do is add a custom alien grenade in terrains.rul (elerium in UBASE is added
this way), on top of the elerium, and then messing around whit the item properties: battleType: 2 (Ammo), clipSize: 25 (turns left), meleePower: 25 (also turns left) as described on the Pedia.
I was thinking that the rulesets was used the same way as OBDATA.DAT is used on original game.
My fault
In short, what I ask you (if you are willing to do it) is to add a way to insert a pre-primed bomb
in the battlescape. Then modders can place this item via terrains.rul.
Citing the Pedia for possible usage:
One practical application of this is to create exploding elerium pods that will explode after a pre-set number of turns
Set the damage to strength to something insignificant like 1 to let them wink out of existence (for data disk autodestruction after x turns).
Regarding second request: flat cost would be a great improvement already
If you are just worried about localized messages, why don't use some dull pre-made string
like STR_DISABLED: "Disabled"?