This question is related How to address a female friend, although somewhat different in its focus.
As far as I understand, the following is true:
If the speaker is female, then "подруга" means "friend" and "друг" means "boyfriend".
If the speaker is male, then "друг" means "friend" and "подруга" means "girlfriend".
1. Is the above correct?
From the answers to the other question, it seems like the only way to refer to friends of the opposite gender is via their name.
2. So is there no way to talk about the relationship in the third person, i.e. no translation of "So-and-so [of the opposite gender of the speaker] is my friend"?
The above is particularly important to me because I don't want to offend my friends by accidentally telling other people incorrectly/falsely that we are in a romantic relationship.
3. How do people refer to romantic partners of the same gender in Russian? Or is non-heterosexuality sufficiently taboo in all Russian-speaking societies that people never acknowledge such relationships or develop words to refer to them?
4. How to translate, without ambiguity, in all possible cases, "platonic friend" and "romantic partner" into Russian? Как правильно описать все отношения по-русски?
I don't really expect a satisfying answer to this question, since the exact same problem exists in German and I have never heard a satisfying answer to that question either. I suppose it is also worth noting that in English some women refer to their platonic female friends as "girlfriend", although I imagine this usage has declined with the normalization of non-heterosexual relationships in English-speaking countries, or at least in the United States.