OMG! Overtext! How long have I been sleeping?! OVERTEXT! Also, I'm a DESIGNER now?! Sweet! OVERTEXXXXXXT!
HO HO HO! Give me some money!
I am not the most experienced player for this one, but I am quite certain I can answer all of these.
(i) Are you obliged to sell an amulet to another player? Can you refuse?
You may not refuse the sale. If your minion is producing (manufacturing), then other players may buy from you whether you want them to or not. Note that a minion carrying an amulet is not producing even if on their home terrain.
(ii) We found that where there were two 'other' minions on a space, a neutral and another player, one would always buy from the neutral so as not to give a 'good' to an opponent. It could be that you might have two other player 'sellers' available - is it your choice who you buy from?
Yes, the active player chooses which minion they purchase from. (And, yes, that means you'll choose a neutral minion when you can.)
Some of us moved a neutral minion onto our home space and bagged the amulet instantly - is that allowed?
The short answer is no. Here's why. In order to purchase an amulet, you need to have one of your own minions present. This is true even at your tower space. (The tower may not make the purchase.) The Amulet Purchasing phase takes place after the Movement phase. Amulets may only be delivered to the tower at the end of the Movement phase. Thus, the purchasing minion must wait a turn to make the delivery.
Does the tower take the place of a minion on a space, thus a tower and 3 minions on a 3-minion space is over-crowded?
Absolutely not. The population limits refer only to the number of minions.
Congratulations. Now you've got me itching again to find a copy of this little wonder. =)