1. Misspelled mispelled...gah.

2. August 24th Theory:

Recognized as the 116th letter of K2, the position of the U misspelling inUNDERGRUUND may be mapped to a calendar. Typically calendars are January-December. If we map K2, beginning with Jan. 1st, then we would arrive at April 26th (April 25th for leapyears). However, if we start with May 1st, then 116 days falls on August 24th. 8/24. K3 can be solved using these two numbers. The OP introduced the elegant solution of first breaking K3 into columns of 24 and then columns of 8, but it can also work the other way around as 8 columns first and 24 columns second:

8 columns
Code:
```OOIAULMPNNITNEASHYABEALS
UMTITABITDIHDFCITWREBIYL
STHLPMENHLNETTHMRATRRNSO
EHISRERGEESHHHIAESOEISLW
EENOETCFHAEOEANDMRFDSOOL
AMEFSOARONRLNNTEBETTTFWY
NIMTEFUOTDTEWDHALMHHHPLD
YSEHNLSMAPEAICETIOEEAAYE
TTRETIETIEDLDOUINVDLTSTS
HXGRLCDHRETIERPNGEOOESHP
ICEOYKTEERHTNNPYHDOWNAEA
GNFMEREHCDCLNRRRNIWRUEEA
QYRWTBFAAIAEGALEDTAPMDMT```
24 columns:
Code:
```SLOWLYDESPARATLYSLOWLYTH
EREMAINSOFPASSAGEDEBRIST
HATENCUMBEREDTHELOWERPAR
TOFTHEDOORWAYWASREMOVEDW
INYBREACHINTHEUPPERLEFTH
ANDCORNERANDTHENWIDENING
THEHOLEALITTLEIINSERTEDT
HECANDLEANDPEEREDINTHEHO
TAIRESCAPINGFROMTHECHAMB
ERCAUSEDTHEFLAMETOFLICKE
RBUTPRESENTLYDETAILSOFTH
EROOMWITHINEMERGEDFROMTH
EMISTXCANYOUSEEANYTHINGQ```