Not enough to notice it before I get a compost yard going. I’m too busy with the essentials of gettting initial 4 houses built, well, firewood splitter, smokehouse, hunter/fisher/forager for food, sawmill, tannery, fletcher building, stockyard, storehouse and market when I have 8 houses. All those things come before I’ll put a compost yard down. All that is done before any icons re waste appear over the houses.
No, you don’t. Not since v0.7.6 came out.
So yes, you will see an icon saying it’s full, but it will still keep collecting whether you have any fields to put it on or not.