several issues are fixed already, and some you are wrong about, but some will never be fixed. So it's really up to you.
Tactical Combat: Brad has stated that this will *not* *ever* be a part of GalCiv. It's supposed to be "Civilization in Space", not "Master of Orion Clone". You didn't have tactical combat in Civ either. So, if this is a must for you, I'm afraid you have the wrong game. But do try to enjoy it for its strengths.
Diplomacy: On the right side are the AI's assets, on the left are yours. If you click on an asset on the left, you are offering it to the AI. If you click on one in the right, you are asking for it. If you choose something from both, you are making a trade proposition. It's simple, really. And on the main diplo screen you get a "relations" bar. Plus, on the diplo screen itself you can click on the three buttons over the center area (below the pic) to see reports about the AI, including what they think of you. As you see, what you want is already there.
Cultural Influence: This is one of the main four ways of ending the game. You want to take it off? Might as well take off those spaceship thingies, they're getting in the way by attacking me
Starbases: They are not supposed to attack spaceships, the help they provide is by bonuses to combat when fighting in their sector. They help a LOT, trust me.
Minor Races: Are you aware that you can also trade/have diplomatic relations with them? There should be a "Minor Races" tab on the external relations screen that allows you to turn a minor into an incredible boon to your civ. Try it.
UP issues: This is there to add some variety. You can turn it into an advantage if, before a metting takes place, you buy/extort (on the diplo screen) influence from the other races. This will give you extra votes in the UP, allowing you to cream the other races.

Besides, the "share all tech" issue has already been toned down in a patch. Get that
Too early events: This has also already been fixed.
I hope I managed to demonstrate to you that the game is really not as simple as it appears, but almost everything has a reason for being there. What mistakes Stardock makes (like to too early events, or using selling tech as an exploit) are usually fixed within a couple days (the patch that fixed all these issues was published on a Sunday Night, fer chrissakes).
So please, give the game another shot, and try to see it for what it is, not what other games are (tactical combat)
Have Fun
Astro
~SDC~