CH 17;- Catherine's delight at being invited.

..she was to be for weeks under the same roof with the person whose society she mostly prized — and, in addition to all the rest, this roof was to be the roof of an abbey! LOL.

CH 23;
Catherine's opinion of the general, we know. And even his dignified step,
...which caught the eye, but could not shake the doubts of the well–read Catherine,

I feel that JA herself is laughing at the well-read Catherine here.

CH 23;
Catherine's, and the General's ;-) inspection of the rooms.

...her indiscriminating eye scarcely discerned the colour of the satin;[..]
the costliness or elegance of any room’s fitting–up could be nothing to her; she cared for no furniture of a more modern date than the fifteenth century.

Therefore:
..... all minuteness of praise, all praise that had much meaning, was supplied by the general:

CH21;
Why on earth would Catherine be interested in a chest and find it mysterious.
Because Emily had one in her room too which was too heavy to be moved to block the door that *could not be locked*. Emily could never open the chest, even with help of her aunt's maid Annette, and the mystery remained a mystery.

Catherine's desire to solve this mystery;
I will look into it — cost me what it may, I will look into it — and directly too — by daylight.

JA's 'gothic' language is so amusing all through these chapters.
The chest was - well calculated to interest an alarm.

The first night - Hollow murmurs seemed to creep along the gallery, and more than once her blood was chilled by the sound of distant moans. (Almost directly from udolpho )

In her room - The window curtains seemed in motion.
................the lock of her door was agitated, as if by the attempt of somebody to enter.