Should I trust the estimated 4-5 hours for the calibration and 7-8 hours for the test charts?
No, it takes around 1.5 hours.
I still didn't get linear 2.2 gamma (Unless I'm mistaken and that those settings weren't for linear 2.2?)
The settings are for linear 2.2, but there's no guarantee that it can be achieved.
I'm curious as to why you chose the text view mode?
The Text View Mode provided slightly better preset results accuracy my unit. Look at the files in HCFR and you'll see.