The most annoying typo IMO is the election one - "Your party continues to control of the Senate". It's just that I see it every time there is an election - starting to bug me! But the fact that typos are the biggest annoyance in the game is probably a good sign!
About the Arceans attacking you insead of the Drengin - The AI will take many things into consideration before declaring war. It is likely that the Drengin were very powerful militarily (they usually go for big fleet/military tech) so the Arceans won't pick a fight with them. So it is not a bug merely another example of the great AI in this game!
Well the first couple that get there will set up trade routes just fine. Once you reach the max. amount of routes you will get a message that says "we have reached the max amount of trade routes as prescribed by galactic law" if you try to establish more routes. I guess you will just have to have your freighters sit around until you research tech that gives you more trade routes.
That's right - even if the relationship is friendly it won't appear. I think this is because the AI will definitely reject an alliance unless you are "close". I understand that this is because the developers didn't want the alliance victory to be too easy. If you could bribe the AI into an alliance political victory would be extremely simple. Instead you must cultivate relationships through trade and gifts. Quite a good feature IMHO.
Make sure that your relationship with the civ you want to ally with is "close". Otherwise the Alliance option won't appear in the diplomacy screen. To achieve such a relationship you need to either give them tech/money or trade with them. Hope this helps.
Another point is that if you leave the United Planets, no one will trade with you.
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