1. Abilities from ECM, Talisman, etc. do apply to an entire stack if just one unit has the components. So I can equip one fighter/WP with a small ECM (or whatever) and it will affect the entire stack.
Correct.
2. For combat purposes, units are not considered to have components that are damaged individually. Therefore armor offers no better protection than any other component with the same tonnage (in which case unit armor would seem to be a waste).
Close, but no cigar. We're talking about
damage structure, not
tonnage structure. Armor III, for example has a tonnage structure of 10kt, but a damage structure of 40kt, so one piece of Armor III donates 40kt of damage structure to the unit. Most components damage and tonnage structure are equal, but not armor. Thus the advantage of armor.
3. Unit shields are not treated as shields, but rather as extra tonnage, even though the unit display will show blue shield points. Therefore weapons that will skip shields have no real effect on units, since the shield points count as kT points and must all be destroyed anyway. (Question: does this mean that a shield generator component gives damage resistance both for the component's kT and for the "shield kT" generated by the component?)
Correct. A shield donates both it's damage structure and it's shield points to the total unit damage structure. (Shield points are converted 1:1 into damage structure. Am I correct?)
4. The Crystalline Restructuring facility does add to "shield kT", either to each individual fighter or to a stack of fighters, depending on whose advice I listen to. Is this also true for other units?
I think so. I'm not sure about WPs, though...
One Last thing: can someone tell me whether the stacking of abilities in number 1 above is an intentional feature or a bug? If it is a bug, I would prefer not to take advantage of it.
Not a clue. Sorry.