I could ask my questions here, of course, but I feel kind of stupid for asking such a simple stuff. Here's a few examples of questions:
"How this type of Ancient Chinese hairpin was called?"
"How medieval European loincloth you see on some knights worked?"
"What they used to cure stomach ache /cold in A country during B period?"
And so on.
The questions of these sort are endless and have quite a variety.
Three main categories I can narrow down are: 1) in-depth fashion history (down to smallest details); 2) Common medicine and 3) daily activities (like cooking, games, chores, raising kids, etc).
Are there any specific books/resources/people I can reference for such sort of trivia?
There are no books that will give you entirely in-depth/detailed information on all of fashion history, but you might like Phyllis Tortora's Survey of Historic Costume. It is a standard textbook used in classes for western fashion history and does have a lot of information. The Greenwood Encyclopedia of Clothing Through World History is broader, including non-western clothing, although I cannot remember how detailed it is.
The Dictionary of Fashion History is, like Tortora, western-focused, but is extremely detailed and easily searchable. It is, as the title suggested, strictly focused on defining terms, so it may not be as helpful for looking things up in reverse (ie if you know the name of the type of hairpin, you can find it, but you may not find it so easy to work from "it's a type of hairpin that looks like this" to the name).