This is an unit/trigger question.

How might you make it so that for each kill that a unit gets, that unit gains damage points? It would not be a "global" ability/trigger/upgrade/whatever, but it would apply differently to each individual unit of this type. I can't use single variables because the creature i want to have this ability can be freely bought, and there is no trigger to just increase attack. (the one thing that they didn't put in... -_- )
Please help. :(

there is one way, make them heroes then increse there strength/intelligence/agility depends on what main atribute you give em

Is there a way to keep certain heroes from being shown where they are dead in the upper-left hand side of the screen? (you know, the portrait turns dark and when u revive them it brightens up?) How might I remove that from just that one unit, but still have other hero portraits? (i will have heroes in the map)

Im not exactly sure if it works but use:
event-unit dies
action-remove triggering unit form the game

ill look it up and see if i can help you

in the object editor look at the 3 values under Stats - Hero -

You can also modify a unit's attack damage with modified "bonus damage" item abilities that you turn into unit abilities. Just make bonus damage abilities +1, +2, +4, +8, +16,... and then, with combination of these, you can get any damage bonus (well, the more you have, the bigger damage bonus you can get) and also, by analyzing, which of these abilities the unit has, you can determine, what it's current damage bonus is.

The abilities leave no icons, because they are item abilities (that's not true for all item abilities, but it's true for most, including damage bonuses).

The method to determine which abilities are needed is by looping from higher to lower damage bonuses: let's say you want to add a damage bonus of 10: first you check for 16, and you see that 10 is less, so you do nothing. Then you check for 8, and you see that 10 is more, so you add the +8dmg ability to the unit, and you substract 8 from 10 (that gives you 2). Now you check with the number 4, and 4 is more than 2; again you do nothing. Then you check with 2, and because that's equal to the ammount of bonus damage still required, you add the +2dmg ability to the unit, and substract 2 from the damage-still-required. Lastly, you check for 1; again, 1 is more than 0, so you don't add the ability.