Actually, no. It's just the male version of the adjective, as the neutral is Stare and the feminine is Stara.
But, for plural for MALE and HUMAN would be Starzy, while for FEMALE and EVERYTHING ELSE would be Stare (for plural) as of: Stare kobiety and singular would be Stara kobieta.
you're right but in Poland we don't say "stary pomidor"only niesmaczny lub zepsuty
Are you sure? I am pretty sure I use it. The ones I bought earlier, or the too ripe ones.
Yes, to me as a native Y and E aren't even similar... but to the learners, that is very problematic. I guess you just have to listen to Polish a lot :/