New answers tagged plurals
It is not that it can't be used with nouns. It cannot be used with anything that is inanimate. Thus, since a picture is inanimate, 絵画たち would be ungrammatical. You should just use 絵画 regardless if it's just one or many. There won't be misunderstandings if the number isn't important, and if it is important, you should specify it, even if the number is general ...
I am convinced you are already aware that Japanese has no plural construction for nouns, adjectives and verbs in general: the Japanese (speaking people) have to guess from the context, hence prone to misunderstanding. That said, I will write down individually. Pronouns are easier to handle as you wrote. 私 -> 私達（わたしたち）or 我々（われわれ） 貴方・貴女（あなた） -> ...
Yes, it refers to one or collective one. こちら can be (1) "this one" or "our side" when the other one ("that one" or "their side") is already present in the context, or (2) a polite form of これ or これら. The latter usage wouldn't be decent in your context. So, that こちらの is "this" opposed to the aforementioned.
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