Check my grammar

#1

If I understand it right.

Koko only for location like(koko wa gakko desu).
Kore only for items(kore wa pen desu).
Kono for random stuff like(kono wa inu desu).

#2

Not quite… これ can be any “thing”, as long as it is physically or psychologically near the speaker. It can be physical, abstract, or a place too. It just means “this.”

この is prenominal (before nouns). You can’t say このは[something]. You can only say この[something]

In English we don’t differentiate between the “this” in “this is a pen” and “this pen”, but in Japanese they do.

これはペンです (this is a pen)
このペンです (it’s this pen)

#3

And koko also means this, which “this” can I refer to.

#4

You were right that ここ is limited to locations. It can’t be used as a generic “this.” It means “here,” whether that is a physical or abstract place.

ここはがっこうです does not mean “this is a school,” it means “here is a school,” even if English speakers would say “this is a school” to mean “(this place / here) is a school.”

Thinking about Japanese grammar in terms of English grammar (too much) is not a great idea. Obviously everyone needs a foothold to start from, but don’t get caught up on translation details, because translations have a variety of purposes, and being one-to-one grammatical representations is usually not one of them.

#5

Ye I have noticed that. I really just want to think Japanese without my dutch or english.
Same when I speak russian I really just speak it without thinking in another langauge and I know what I’m saying. But I quess it’s alot of practice and before you know that english translation voice in your mind will shut down.