So the word "собака" (dog) is feminine. How would you describe a male dog in Russian?
Female dog=сука (it's as abusive as "bitсh" but more widely used), male dog=кобель. But these words are used only when you want to stress dog's sex. Пёс (male dog) is rarely used these days.
It is not true. "Собака - моя" = The dog is mine, "моя собака" = my dog. Possessive pronouns go before the related noun just like adjectives (having the same endings). Genitive possessive noun goes after the related noun. It's not really variable.
Their grammatical form is the difference.
- мой masculine, singular
- моя feminine, singular
- моё neuter, singular
- мои any gender, plural
It is a possessive pronoun and they work like adjectives. Genetive with possessive role is only applicable to nouns and personal pronouns.