Was George Orwell an Optimist?
Randy Weston - The Spirits of Our Ancestors
1.) Does movement among your friendly-controlled territories require a terrain card?
Second sentence in section 11: Geographical Barriers: "Yang cards are necessary to cross all barriers DEFENDED by a competing state."
(The caps aren't something I've added; that's how it appears in the rules.)
2.) If you control a token only by inference do you still get its benefit?
Last sentence in section 7: Economic Symbols: "A province which has become depopulated through Yin misfortune or withdrawal requires re-population from adjoining territory."
Also note the line in 6: Movement of Population Markers: "It is necessary to leave a marker behind only if a province possesses economic wealth, or if an escape route is desired."
3.) When are stacking limits enforced? We played you can overstack during placement but have to move out right away.
Excerpt from 6: Movement of Population Markers: "No more than TEN population markers may be in any one province at any given time: excess markers (except during the securing placing phase) must be removed from the board." (I've added bold font to emphasize the key phrase.)
4.) Can a defender force an attacker to spend his terrain card, then just withdraw? Or must he endure at least one round of combat if he does not accept a withdrawal offer?
I've seen people house rule that if he plays a card, he gets his first roll, but that's not really in the rules. Remember that you cannot withdraw into a territory where you don't already have at least one unit, and that stacking limits apply.
The rulebook suggests bluffing a terrain card so you can move without spending one, but then seems to say defenders can withdraw from battle at any time... so bluffing would be pointless because you can always force someone to spend his or her card, then just retreat from combat.
That section is prefaced by the word ADVICE in caps, to make clear it is advice, not rules. What it suggests is that you use diplomacy to get an opponent to withdraw by convincing them you have what you need to eliminate them if they don't, the implication being that he would withdraw on his own turn before you attack him on yours.
5.) When a player merges into a stronger empire, are his tokens physically removed from the board and replaced with an equal number of the stronger empire's pieces?
It works better if you don't; giving the stronger player control of both colors.
6.) There is some gamey-ness in the endgame where you can tell a player you will offer a merge, then have them retreat a couple territories, then absorb them so you can maximize the number of territories you will gain. This is a bit hard to describe I suppose, but if you only have 1-2 pieces off the board you can replace the defunct empire with, it will behoove both players for the weaker empire to sacrifice a few territories and THEN merge.
See above; if the stronger player controls both colors there is no issue.