Aldarian race? i have never seen sur a race in MOO3. Is it the name of an Empire? Do you mean the New Orions, the Antarans? they despise you and i haven't been able to talk to them yet either. I know that once they respect or fear you, they start to talk to you :notsure:
3000 turns is way too much and probably due to the fact that you play unpatched.
For the patch try Apolyton: http://apolyton.net/moo3/
Concerning building DEAs. Some aspects have been corrected in the patch. However you have to remember that on each planet you have a viceroy. He decides what to build. You can give them an indication on what they should build with the developpment plans and they'll follow it as good as they can.
You can have only have 10 Task Forces(armadas and so on) to attack a system or to fight another fleet. So if you have 10 Long range TF and 2 troop TFs on orbit, chance is that you'll have 10 LR TF waiting around an undefended plannet = no invasion possible. So send two LR TF back.
As i mentionned before, Armadas are not enough to find the X. You also need better ships. Will you loose some? sure...will you find an X, yes,i've done it so many times.
Is the game out of the box a shame? YES IT IS!!!! the game should never have been released as was. The patch is very good. I really hope you can download the patch and give it another try, there's a good (not perfect) game beneath. I wouldn't want to play it unpatched either