I just want to double-check that all of these are right. In all cases, I bought Travelling Fair earlier in the turn.
1. I buy Border Village and gain Bridge. I can put them on top of my deck in either order (because Border Village's effect is on gain, not on buy).
2. I buy Stonemason, overpaying, gaining BV then Bridge and BV then Procession. Depending on the gain order, I can do (BV and Procession) in any order, and (BV and Bridge) in any order, and I could have switched those two groups if I wanted (I could have done (BV and Bridge) then (BV and Procession)), but if the Stonemason's going on top of my deck, he's the last to go, since the overpay effect happens on buy. I couldn't finish with an ordering like BV-BV-Bridge-Procession (if the BV's are consecutive they have to be in the middle).
3. A Haggler wants to join in on this party. I can resolve it before or after the Stonemason overpay effect. So I can go like Poor House-((BV-Procession)-(BV-Bridge))-Stonemason or ((BV-Procession)-(BV-Bridge))-Poor House-Stonemason, where the parentheses denote that I can choose the ordering of the stuff inside them. These are my only options.
4. If I am doing some shenanigans involving Stonemason, BV, Haggler, etc., I can choose to put anything I want in my discard pile and anything else on top of my deck. There's nothing stopping me from putting some on top of my deck and some in my discard pile (barring Nomad Camp and Villa).
5. If I gain Villa, it goes to my hand, assuming that's where I want it. I could also choose to have it go to the top of my deck. I could not choose to have it go to my discard pile.
6. Hagglers gain stuff from cards bought via Black Market.
7. Bridge reduces the cost of cards in the Black Market.
8. Are there any official rules for setting up the Black Market with split piles?
9. Cards bought from the Black Market end up on top of their Haggler gains.
I think that's all for now, but I might come up with more later.