Keep in mind that there are only 12 build actions available in the entire course of the game
How come? You didn't mention any hard limit, apart from the 100 respect one.
You can only Build in Spring, Summer, and Winter, and the games goes for 4 years. That's 12 build actions (not counting anything you get from Tales Cards). So it's a built in limit, not a hard rules limit.
Why not make wooden fences generate like 0.5 respect per year and stone fences like 1?
I'd rather give them some Farming bonus instead, if I was going to do that. But to an extent I want to keep things simple. Lots of complicated rules makes a boardgame unwieldy.
Also, you missed a bunch of questions:
1) When a building 'replaces' some other one (i.e. Grand Hall in place of Long Hall), do we need to build the building being replaced before building the replacing building?
2) Do winter-specific events get added to the global event pool with the equal probability of being drawn, or do they happen independently from other events?
3) Can I place my new Laborers after doing this turn's actions?
4) Is there any limit on how I can trade with other players? I.e. can I trade with Scelly on the other wide of the map without either of us having road and there being both uninhabited regions and regions settled by other players between us?
You keep editing without me noticing.
1) A 'Replaced' bulding just means that if you had one of those, it's gone and you just have the new one. So if you had a Long Hall and build a Grand Hall, you lose the Long Hall. You don't need a Long Hall to build a Grand Hall, though, and generally it's a waste of materials and time to do both.
2) There aren't any Winter Specific Events, although some Events will make more/less of an impact depending on when they show up.
3) No, you have to place them before the Action Phase (so, no, you can't Explore first and then place them).
4) No, no limits on trading with other players. They're not that far away, in the grand scheme of things. And unlike trading with the Homeland there are no limits on the amount of stuff you can trade between one another. (Well, between Food, Goods, and Resources)