Emile de Maat
1) If you choose not to place an Influence Disc onto a tile after combat (because you can't afford the upkeep or possibly some other reason), when is your next opportunity to place that disc? Is it only during the next round's Action phase via the Influence Action, or can you wait until the end of the next round's Combat phase and then place it for free (assuming you still have at least 1 ship on the hex)?
Since the rules on placing influence after the combat phase explicitly state:
Eclipse rulebook, page 21 wrote:
Also, if your Ship is in a hex without an Influence Disc after the Combat Phase, you may place a disc there.
It seems clear to me that you may place a disk after the next round's combat phase, regardless of whether combat actually occurred or not.
2) I'm assuming your ship blueprints must always be viable, correct? So you can't upgrade ship parts that you don't have enough energy for yet and then add the necessary Source next round? Assuming you don't have any of the relevant ship class built, of course.
Correct. There's nothing in the rules that allows for your blueprints to be not viable temporarily.
3) Can you engage in Diplomacy when it's not your turn? Or just at any time during any one of your actions in the Action Phase?
The rules say:
Eclipse rulebook, page 11 wrote:
Diplomatic relations can be formed at any time on your turn.It seems you can only engage in Diplomacy in your own turn (or when responding to another player's request, of course).