When and how did Guts meet Godo? I don't remember it being clarified or not, I'm guessing that they met through Godo making armor and weapons for various mercenary bands when Guts was a kid. They seemed to have an interesting relationship and I hope Miura goes more in-depth about it someday.
Guts met Godot and Erica while traveling alone, after he left the Band of the Falcon. It's explained in the first episode of volume 10,
Sparks. I don't think we'll get to see more.
I view Godo more than just "the guy Guts goes to so he can repair his gear" he almost seems like a father to Guts, giving him deep life advice and such.
"A father" is a bit much, but he did give Guts advice that rang true.
While I'm talking about Godo, why was he exiled for making the Dragonslayer? That didn't really make sense to me. King: "That sword is huge! Kill him!" what?
Well then you should probably re-read that part of the story? A king issued a proclamation, asking for a sword that could kill a dragon. What he wanted was a grand and magnificent sword, but Godot took it literally, on purpose, because he was bored with working for nobles, and created a sword that was truly made to kill a dragon, and was therefore unuseable by a normal man. When he presented the Dragon Slayer to the king, the man was most likely offended because he felt that Godot was making fun of him (which he was). I don't think it's too hard to understand.
Here is a good translation of the scene, in case you need it.
Secondly, I think after Berserk is finished, Miura should make some bonus material showing each of the original Band of the Hawk member's pasts. It would put even more character development into them and would give the series/golden age arc even more re-watch/re-read value than it already has, and make the Eclipse that much more tragic.
The Golden Age arc has long been over. There's really little interest in revisiting the characters who died then, especially since we already know the outline of what they did before we were introduced to them. I really don't think Miura will be doing that when Berserk is done.