When i'm looking at the upgrade cards such as the determination it looks like an imperial card with that big vader face on it.

But i can not find anywhere if there is upgrade card wich is for only the rebels or the empire?

Same for the squad leader. I only have 1 core set and 1 copy of each of the expensions. There might be a fight of the only squad leader card or does it belongs to the empire?

Upgrade cards are limited by the icons on the ship cards and the upgrade cards. Currently, there are no Imperial or Rebel icons, so no upgrades are limited by faction. Some are limited by icons. No Imperial ship currently available has an astromech icon, so only Rebel ships currently may purchase astromech upgrades. Likewise, no currently available Rebel ship carries a missile icon, so missiles may only be purchased by Imperial ships.

Note that some of the YT-1300 ships DO have the missile icon, so when those become available, Rebel builds will be able to purchase missile upgrades.

I don't think we will see a Imp ship with astromechs. So while not technically specific to the faction, they are de facto. They do have faction specific crew members (Luke, Chewie) for the new "crew" upgrade. Probably there will be a faction specific Imperial crew with the Slave 1.

A-wings will also have the missile upgrade.

Presumably (not certainly) the Slave 1 will have cannon upgrade so that it can have an Ion cannon like the Y-wing. And I am holding out hope that this upgrade will also be non-faction specific, so that the Y-wing has more upgrade options, invigorating its place on Rebel squad lists.

Wave 2 will introduce faction specific upgrades, but from what we've seen those will be clearly identified on the face of the upgrade.