The Alliance mod comes now to Sins of a Solar Empire games with all the space units which you can find in mod from the Star Wars Empire at War Force of Corruption.
Destroy the Death Star is a difficult, it has a strong armor and a super laser with a short recharge time. However, it is very vulnerable to the fighters and the super laser has a short range. My recomendation is avoid it with your capital ships and launch all your fighters against it. Have fun.
who needs to destroy something when you can steal it