My findings:
I completely agree with your findings. I'd like to add a few things I've found about mines:
1) Mines decide where they will target their 5 mortar bombs randomly within a square of dimensions 20x20. The mine is located in the lower right "middle" of this square. The bombs cannot fall on top of the mine, so there are 399 possible squares for each of the five mortar bombs. Distribution seems rather uniform to me, although I haven't tested it enough.
2) The central explosion of a mine is the only thing that can inflict damage to creeper while the game is paused (by manually destroying the mine). Of course, you will not see the creeper changing colour or disappearing until the game has been unpaused and possibly several frames later, when the creeper gets redrawn. However, you can see the damage when the game is paused, by hovering your mouse over a square near the mine and looking at the elevation gauge.
3) This point is a bit more subtle. So, first of all, I'll have to revise how the various "bullets" decide the damage they make. So bear with me. Each of them has three constants attached to it: number of squares, depth, radius. For example a blaster "bullet" has 8 squares of depth 1 and radius 8. Once a blaster has chosen the target, it will look around the target in an open disk of radius 8. It will do damage up to 1 to the target, and then will start looking at the squares of the disk in some order (roughly from near to far), until either the disk has been exhausted, or it has found a total of 8 squares with creeper (that also satisfy the requirement that they are of lower or equal elevation to the target). It will do damage up to 1 to them.
Similarly, when a mortar or drone bomb falls, it will do up to 4 damage to the target cell, then start looking at an open disk of radius 8 until it either exhausts the disk or finds 36 or 50 squares respectively and do up to 4 damage to them. That's because the squares, depth, radius values for a mortar and drone bomb are 36, 4, 8 and 50, 4, 8 respectively.
Note that the target square can be targetted twice. The bullet will do damage immediately to the target square, but then relook at it while looking at the (non-punctured) disk of radius 8. This is why a blaster does damage up to 2 to its target cell and mortars and drones up to 8 (and in that case they can only hit up to 7, 35, 49 squares respectively). Technically, it hits the target, then finds that there is still creeper in that cell and rehits it.
The radius thing is demonstrated very nicely in
this thread, where "through-the-wall" damage only goes as far as <8 squares, even though the 36 squares of damage of mortar have not been exhausted. Note that this radius has nothing to do with the range of weapons, it's a different thing completely, happening after the target has been chosen.
The special thing about mines is that their central explosion has a radius of 15! Their constants are 48, 4, 15 (squares, depth, radius). That's, of course, only for the central explosion. Their fragments are normal mortar bombs with normal mortar constants. In other words, the central mine explosion can display "through-the-wall" effects way farther, almost double the distance, than what a mortar can do.
Short story if 3) was a bit too long to read: The damage of central explosion of mine can reach any distance less than 15 cells away from the mine, as opposed to blaster, mortar and drone bullets, that can only reach less than 8 cells away from the target.
I have used these three special properties of mine explosion in the second part of
my latest puzzle map. Admittedly, a somewhat obscure puzzle, but I've been looking forward to posting my findings here on the quiz, so that I can give hints there!
