Yeah. Everyone in the order was kinda friends.

Yes, I feel like he knew them quite well actually.

Yep

He might of

I don’t think we are ever given any indication that they were close.

They were at Hogwarts with each other, and they were in the Order too so, maybe.

I think he definitely must have visited them. Because he taught Neville to overcome his fear so passionately in PoA that he must be good friends with his parents Frank and Alice Longbottom.

I agree that Remus was good friends with Alice and Frank, but I think Remus would teach Neville like that anyway. Remus isn't the kind of person to help someone just because he was friends with their parents (Harry's case was very different; and besides, he'd help Neville with Dementors if Neville had asked him to as well).

@Durga1239 I think you are right. I change my mind now.

I don’t think he was necessarily close with them. He definitely knew them, but it could have been a more casual relationship. Especially since I think Remus generally avoided forming close friendships.