How can I make a unit launch a missile with a (un)limited impact range (that will fly straight in a direction until it hits something) ?
Like I would like a phoenix with an ability that when I press [Space] it would launch 2 small projectiles in front of him, hitting anything on their way. Kinda like in airplane games ...
How can I do that ?
Photoloss Regular Shmoe1) If changing the model asset itself fixes it you probably have to edit the model in an external 3d graphics program. You can try increasing the Art: Radius field, but I doubt that will work.
2) Try ticking the Behavior: Resource Drop Off+ flags on the unit as a test, though I doubt that will work. You'll probably have to make a second harvesting setup altogether, using Modify Unit and Modify Player effects to handle the resources and Persistent effects or Buffs for the harvest delay.
3) Just make an empty upgrade and a Requirement that counts it. Requirements can be stuck on pretty much anything, especially all abilities and buffs you normally use. Look at all the researchable abilities (Stimpack etc.), the Requirement is set in the Commands+ or Info+ field of the ability.
4) If both use the same weapon the upgrade will affect both anyway. Otherwise just add to the Effects+ field on the Upgrade. The system is tied to the data object structure, so damage is determined by the Damage effect of the weapon. There is no way to have several units share a damage effect but not the damage upgrade. An alternative is to give them a passive +10 damage buff with a Requirement to count the upgrade (see 3), this would of course affect all damage of a certain type, but can be useful for TD maps with lots of towers and fixed +x dmg upgrades.
5) I have no idea how you set up your previewer like that :) What you probably want to do is press Shift+D to open up the model properties window, then read the texture names under "Materials". Setting up textures for "select by Id" is completely seperate, go to the Textures data tab and create a new object, go to File->Browse and you should see the familiar list of all texture assets.