Question about the surround bonus

[Huzurdaddi]

I think this is in the manual but I can't find it so I'm asking you guys!

Is the surround bonus/penalty -1 to defence per unit who is attacking or -1 to defence and -1 to protection.

Also is it -1 per attack or -1 unit?

Also are the unit's attacking considered as the turn proceeds or calculated at the start of the turn and applied to everyone the same?

Finally, are 4 squares considered adjacent for this bonus/penalty or 8?

Thanks in advance!