Thanks, that's encouraging. The trade issue remains on my radar and I have log output now to investigate when it occurs in my own games (which I expect it will once I get around to playing).The lack of friendships, also between AI civs, is an open issue. I think it's mainly because bonuses for open borders, shared war and supplied resources are more difficult to attain than in BtS. However, those changes have been in place for a long time. It would be interesting to know which somewhat recent change, if any, has made the AI even more difficult to befriend.

Since v0.94, it's significantly harder to max out the fair trade bonus and +3 is probably harder too. (But +1 and +2 should generally be easier to get than before.)
The Friendly threshold is, effectively, already 1 lower than in BtS (due to the removal of -1 "first impression" on Noble difficulty and above). I'd like to lower it more, but 10 is a much nicer threshold than 9, and, at 9, the symmetry with Furious may have to be broken – the AI already gets Furious quicker than I'd like. Bizarrely, the thresholds are hardcoded in the DLL (I ought to change that). So, since I don't suppose you're using a custom DLL, I can't even recommend adjusting the Friendly threshold. (If all thresholds are too high, then +1 "first impression" through Civ4HandicapInfos.xml could be used as a makeshift measure.)
I've been meaning to add a new modifier: "+1: The enemy of my enemy is my friend" for being the worst enemy (or a war enemy?) of someone's worst enemy. I don't think that's going to be enough to set the balance straight. There don't seem to be many good reasons to like a player.