Ghouls are unable to digest anything but human meat, and, while it's noted to be significantly less appetizing, ghoul meat—aka cannibalism (guess the hard skin and, ya know, eating your own kind doesn't sit well in the stomach). Kaneki can't eat hamburgers (beef), we've established this.
They will feed on any available source of human meat to end this state, even that of close friends, as shown when Kaneki was willing to eat Hideyoshi Nagachika, his best friend, before being stopped by Touka Kirishima. She describes this state of near-starvation as, "hell for any ghoul".
Only the Quinx Squad are able to consume human food including Sasaki Haise and even Arima. Ghouls differ from humans in having high RC Count. The More the RC, the more ghoul like features you have.
In their case, however, only eating ghoul meat is typically treated as cannibalism. Ghoul meat tastes disgusting to ghouls, but in contrast to other non-human nutrition, they are able to digest it. Continued cannibalization may trigger a mutation in Rc cells, resulting in turning them into kakujas.
The only thing that can kill a ghoul is decapitation or complete destruction of the head. Bashing their brains in works as well. Ghouls are capable of leaving behind identifiable fingerprints that can be matched to them at the very least while they are using a single form.
No a ghoul could not drink tea the same way they can drink coffee. Yoshimura said about coffee being the only thing ghouls can enjoy like humans. Tea is not palatable or digestible to ghouls in the same way coffee is.
Besides water and coffee, a ghoul can only feed on humans and other ghouls. They are unable to digest any other type of food due to a particular enzyme their bodies produce. The structure of their tongues are also different from humans', making other foods taste disgusting and uncomfortable.
A ghoul would not be able to drink coffee with cream and sugar. The cream should be obvious as it is literally made from cow's milk. The sugar is a little differant.
Yes, butter freezes very well, so feel free to fill your freezer! It's not unusual behavior to stock up on butter, as running out of butter can be a hassle. Freezing butter is a very good way to avoid this inconvenience.
To get there go to Tools > Options > Document Properties . In the Detailing section, there are two options that need to be selected, 'Cosmetic threads' and 'Display annotations'. If you are looking to add a shaded view of cosmetic threads in the hole, the option 'Shaded cosmetic threads' will also need to be selected.