Droomhuis

Yes — if you choose the leftmost column you take the bottom card and the first-player marker; if nobody chooses the leftmost column, the current first player keeps the marker for the next round. (p.4)

No — rooms cannot have an empty space directly below them, basement cards must go on the two basement spaces, and normal/unique rooms must be placed on the top two floors. (p.6)

Normally placing a décor token finishes that room and it cannot be expanded further, and a room that has reached its maximum card size is also finished. The Interior Designer helper is an exception: while you have it the décor token does not finish the room during the game (though it still limits to one décor), and each décor is worth extra points at the end. (p.5, p.7, p.13)

Place the card facedown on an empty space of your home board as an empty room (worth 0 points); empty rooms still must obey placement rules (e.g., no empty space directly below) and cannot be expanded. (p.6)

You place roof cards facedown as you take them, then at the end reveal and choose four to form your roof: a uniform four-of-a-kind is 8 points, a mismatched full roof is 3 points, incomplete roofs score 0, and each window on a complete roof adds +1 point. The Roofer helper lets you add one discarded roof card to your stack at the end, but you must use it before looking at your facedown roof cards. (p.10, p.11, p.12)

Tool cards are used during your turn unless specified otherwise: Drill is discarded at the start of your turn (before choosing a column) to swap a room on the game board with one on your board, while Jackhammer is discarded at the start of a round (before the first player chooses) to immediately take one room from the board and then you skip your normal turn that round. (p.13)