Neonchameleon
Legend
No. I'm saying that in my style of play character knowledge and player knowledge is the same. So whatever you choose to do you are already basing it on character knowledge alone because as DM that is all I'm giving you.
And this is where I have little understanding of where you are coming from.
As a player I can not see what my character sees. I can not smell what my character smells. I don't know the history of the world or the smell of salt air on the breeze in the way my character does. No matter how much the GM describes I will not and can not see the setting in the same detail as my character unless my character is literally blind and being guided around by someone describing things.
Also as a player my character is unable to look at their own character sheet. My character can't say how many hit points they have left, and far from an exact knowledge of their stats they normally have a version of the (real rather than cartoon) Dunning Krueger Effect, thinking they are a bit above average no matter whether they are poor or exceptional. And they certainly don't have objective information that way.
I often try to approximate the two as closely as I possibly can and there are many ways of doing this (and giving narrative control helps in some circumstances but not all).
And then there's background knowledge. The more time a character spends in a city the more they know it. If someone was playing a character who'd lived in a large city all their life and wanted to e.g. find a certain type of second hand bookshop they would know roughly where to find it, and I'd let them describe the bookshop as this (as opposed to exact knowledge of the books on the shelves) would be in character knowledge.
And regarding Fate, last time I played it we were playing Dresden Files. Fate Points were spent for precisely one purpose in the half dozen sessions. It always and without exception happened where the character was saying "This is what is important to me. Here is where I am going to grit my teeth, spend my physical and mental stamina, and make sure I get this right." An entirely in character decision. (And yes, we had remarkably few compels that game). And to me this is one of the weaknesses of most forms of D&D - the inability to pace yourself and to decide when to really go all out mechanically takes what should be an obvious choice in character and means there's no weight behind it.
As for the question of whether to spend hit dice, my normal assumption is that you spend hit dice when bandaging your wounds and recovering your strength. An in character decision to take a rest and to bandage yourselves. How many you spend is obvious - you spend until you are in about as good shape as you think you are going to get with the only question being that extra layer of bandages that will do a fractionally better job but may get in the way (i.e. do you spend hit dice when you are close to but not at full hit points).