Also i noticed that T2 engies can build T2land factories right of the bat
That was not in the base game right?
Sometime i cant upgrade factories to T3
There are support factories and HQ factories. Support factories are significantly cheaper than HQ factories, have the same production ratings but they are weaker in defense. You need to have a T2 HQ in order to make a T2 support factory. Once you have an HQ of a given tech, an engineer of that same tech or higher can right away build a support factory
A work of art is never finished, merely abandoned