[Aiken]

Unfortunaly the AI doesnt like those planet types and seems to never choose them.
So my question is, are the premade planet types (homeworld, research compound, resupply base and stuff) hardcoded ? Can new ones be added, or can existing be deleted ?

I could swear they're hardcoded, though I'm not sure you can delete one of those types. So instead of adding new types, you better edit "useless" existing ones, like Military Installation or Resupply Base, according to you intentions.

or will it add one component for each 100 kT of hull size, so a 100 kT ship will get one, a 200 kT ship will get 2 and so on ?

Right.

What i mean is, will the KI add one component for 0-100 kT hull size, a second one for 101 - 200 kT hull size, or will it add one for 100-200, a second one for 201-300 and so on ?

No, it will add 1 comp for the 0-199 kt hull, second one for 200-299 kt hull, third one for 300-399 kt hull and so on.

In addition, i have a question about the facility upgrade button. Is there anyway you can control how many facilitys will be upgraded or will the button always result in "upgrade all of this facility" reaction ?

I guess you're talking about Construction Queue (by F7) window? If so, it's hardcoded behaviour, and you can't change anything.