I think he did
No Minato doesn't have SM if he did he would have used it during the Tobi invasion into Konoha smh
Let's just say he has SM but didn't have time to collect Nature chakra.
If he was never shown using SM or mentioned using SM I don't think he would have SM
If he was never shown using SM or mentioned using SM I don't think he would have SM
We don't have evidence that he has SM and evidence that he doesn't have SM.
I don't think he could learn how to use sage mode. He had low Chakra levels from what I hear.
I don't think that was ever even implied anywhere.