"Grem came from a farm."

Did he really? Or is Jon being ironic?

Both.

I also think Jon has a soft spot for Mance.  Ned Stark beheaded a man for leaving his watch; Jon spared Mance for his vicious crimes against humanity.

Jon definitely understands Mance and wants to keep him alive.

Free Folk without a leader would be chaos. With a leader at least they can have a truce.

I'm glad Mance said they don't want to destroy the Wall, they just want to get away from the White Walkers. That explains why they didn't overpower the Nights Watch. They need the Wall too!

I'm looking forward to more Stannis-Jon dynamic. I hope Stannis sticks around a while.

Do we know what happened to Ser Alliser? Who commands the Nights Watch now?

I don't know, but someone passed a torch to Sam, who passed it to Jon, who lit the funeral pyre.

Game of Thrones wiki says he's still alive:

They duel evenly for a time, but Tormund finally manages to wound Alliser, who escapes by rolling off the catwalk and falling onto a hay-bale below. The injured Alliser is then carried to safety by two members of the Night's Watch, while screaming for the remainder of the men fighting to 'Hold the bloody gate!'.

I'd like it if Alliser is still alive. I like him now.