The requirements to get Honor level 2 from dishonorable was just lowered in patch 8.6 so it is hard to tell how long it takes to get honor 2. I have a few friends that just now hit honor level 1 within the past few days when they were banned at the start of the season. As far as I have seen, they gain a checkpoint once a month.
As for the five man pre-made, Riot mentioned that being honored by friends gave less than if you were honored by random teammates. Far as I can tell personally, being honored by everyone compared to just one person a game has little affect considering everyone I know hits the same checkpoint within a week of the first person in the group hitting it. It would help if there was a progression bar of some type, but it is complete guess work.