You have ShowErrors set to TRUE in your settings file. Either set it to FALSE or delete the Settings folder to reset your settings.
Don't use the dev exe or set ShowErrors to FALSE in the settings file.
The UNSC AI is far weaker than the Covenant's because the former's ships are based around alpha damage and being deployed in groups. This contrasts entirely with how the AI in Sins works where it is designed around protracted attrition warfare, meaning that it will send ships in piecemeal. Covenant ships, given their superior durability and DPS focused weaponry, will tend to function far better with how the AI operates.
Not a problem; if you have any other issues do give us a poke.
You need to set ShowErrors to FALSE in your rebellion.user.setting and rebellion.user.dev.setting files which are found in ...\Sins of a Solar Empire Rebellion\Setting
This thread is outdated; 1.90 came after this thread was made, and it is as of that version that LAA is enabled by default, and thus people should not do it manually. I'm locking this thread to avoid confusion; if someone is having issues still please make a new thread.
This is very much intentional; as the build description for the ship states, it takes a number of minutes to build, versus the supposed few seconds that the infocard has.
This heavily depends on what faction you play. Are you UNSC or Covenant?
We are aware of the issue and will include a fix with the next public release.