The analyses of a text #2

The narrator recalls his childhood.
He was forced to work for his own living for Mr. Murdstone's friend Mr. Quinion at London by his stepfather Mr. Murdstone.
When the protagonist started to run away to his grand aunt Miss Betsey Trotwood, he was robbed his money and box by a porter and then he abandoned pursuing him after a long distance pursuit.
At last, he arrived his grand aunt's place after a long and rough traveling.
He said his own story to his aunt and her friend Mr. Dick, whom his aunt takes care of.
And he came to start his new life with the name "Trotwood Copperfield."
Now his aunt and he visited a lawyer's house to get an advice about what school he might as well go to.
But it was determined that he would stay this house.

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We accordingly went up a wonderful old stair case, with a balustrade, so broad that we might have gone up that, almost as easily, and into a shady old drawing-room, lighted by some three or four of quaint windows I had looked up at from the street, which had old oak seats in them, that seemed to have come of the same trees as the shining oak floor, and the great beams in the ceiling. It was a prettily furnished room, with a piano and some lively furniture in red and green, and some flowers. It seemed to be all old nooks and corners, and in every nook and corner there was some queer little table, or cupboard, or bookcase, or seat, or something or other, that made me think there was not such another good corner in the room, until I looked at the next one, and found it equal to it, if not better.
[David Copperfield by Charles Dickens]
1. I'd like to know if the underlined "that" relative clause is a parenthesis.
2. I'd like to know if "so" is implied before "that made me think."
Thank you in advance for your help.