Also on diplomacy:
1) Will the player be able to tell which aliens are trying to talk to him? This seems like something that is more likely than not to be obvious.
2) So my understanding is that, for every race you've met, relations will always drift towards the negative unless you have an embassy ship talking to them (in one of their systems?) due to their xenophobia (even if it's only "1"). So if I chance upon an alien scout in a system and we both go our separate ways and don't see each other for 10 years, when I encounter them again they'll want to go to war with me even if they've got a very low xenophobia?
3) Are there going to be any actions that the player can take that will generate positive diplomacy points? For example "upheld treaty commitments" by not entering alien systems for e.g. non-interaction treaty. If not, then it appears that the only way the player can influence things in a positive direction is to have an embassy ship, and the effect of that is capped at one ship. I was originally going to go down the road of making diplomacy modules VERY expensive and allowing more than one, but there's a lot to be said for "actions speak louder than words". Perhaps the diplomacy modifier could put a bias (e.g. +10 points towards the good) on all the other events that happen, e.g. a -50 "ship parked above homeworld" might only have a -40 impact if there's a diplomat.
The challenge I see here is setting things up so the player can positively influence things without having a system that can be gamed by throwing huge resources at the problem - perhaps a law of diminishing returns where the 2nd diplomacy ship is only 80% as effective, the 3rd 64% etc, which would sum up to a max 10x multiplier with an infinite number of ships.
John