Hearing this, the old man turned from anger to delight, bent himself double and said at once, "Please — please come into my poor house and settle yourselves."

著 is the unstressed zhe. 寒舍 — "my cold house" — is the standard modest word for one's own home, and it is arriving from a man who was pointing a stick a moment ago.

So the four of them led the horse and shouldered the luggage and went in together.

擔 is dàn here, the noun: a load slung on a carrying pole. In the poem four segments back the same character was the verb dān, to shoulder something. Noun and verb, distinguished only by tone.

They saw thorn and briar laid out along both sides.

鋪 is pū, to spread out — automatic transcription gives pù, which means a shop.

The second gateway had walls piled of brick and stone, and again brambles thatched over the top.

苫 stays shān. Modern dictionaries split this character into a noun and a verb with different tones, but the 1716 dictionary gives the level-tone spelling as the main entry with the covering sense already attached — "to roof something with grass" — and marks the other spelling as meaning the same thing. The modern split is not what the older authority records, so the older reading holds.

Only inside that was there a tiled house of three bays.

間 is jiān, the bay — the standard unit for measuring the width of a Chinese house, roughly one span between roof-posts.