I am trying to get some similarly spelled words straight in my mind. Can someone confirm the statements below are correct?

Coir: crime. Pronounced with an "i" (kir')

Cóir: adjective: right, just. (ko:r')

Cóir: noun: right justice, provision. Rinne mé cóir duit, I did right by you.

Cóir: noun: presence. (ko:r' with an option nasal vowel) This word was spelled cómhair in the old dictionaries. The first entry on p271 in Ó Dónall's dictionary indicates that this word is now spelled cóir.

Comhair: apparently the word cómhair is spelled comhair and not cóir in some prepositional phases. See p279 of Ó Dónall's dictionary.

It is difficult to understand why in Standard Irish you write "os comhair" "i gcomhair" but "de chóir", when it is all the same word.

Has cómhair been confused into two words in the Standard Irish? Did I get all the above right?