Hello

What did you mean with "play as Asuran"? You know that you just can play as Tau'ri or Goa'uld? But you can as well make the Aurora class Warships buildable, if you have coding experiences and can inscribe it in the right xml and tag. But unfortunately I don't know which they are the right ones.^^

Goto C:\Program Files\LucasArts\Star Wars Empire at War\GameData\Mods\Stargate\DATA\Xml and open SpaceUnitsCapital.xml. Scoll down until you find a ship named Asuranerkriegsschiff.

Scroll down again until you find <Affiliation>Asuraner</Affiliation>.
If you want this ship to be buildable for the Tau'ri change Asuraner to Rebel and if you want to use it as Goa'uld change it to Empire. Delete Asuras in <Required_Planets>Asuras</Required_Planets>.
Then change <Build_Initially_Locked> to No and <Tech_Level> to 1. Finally, change <Build_Tab_Space_Units> to Yes.

If you want to build it in skirmish, I think you can do so on some funmaps already.

Hope that helps

There are several Empire at War xml tutorials in the Internet if you want to know how to do stuff like that on your own

But ok, I'll help you with this one:
If you want to build more than one change this line to whatever number you have in mind: <Build_Limit_Current_Per_Player>. If you don't want any build limitations remove the line at all.

Changing the galactic max unit cap is not thaaat easy.
Open Stargate_Planets.xml and scroll down until you find <Additional_Population_Capacity>. Change this to whatever value you think is adequate. By conquering the specified planet your max pop cap will be increased by the number you have written there. You need to do this for every planet you want to have an effect but the easiest way is to start with your "home planet" in GC.
Alternatively you can change the <Population_Value> for each ship to 1 or 0 but a think that's a "little" more work^^

Starbases.xml...

No, you have to add the Asuranerkriegsschiff to the buildable objects in skirmish tag (can't remeber the exact name now) for each starbase level you want to have it.