The guys who stole the safe are the new Samcro members, Greg the Peg and Chuck Zito and the other one. Why they're interested in the shit in Clay's safe is beyond me at this point, and I can't even guess. It looks like those guys might be working for Clay, but I dunno. That seems a bit too obvious, and maybe too big a play for Clay to be pulling this soon after his gratia excidisti, but the only other option is that someone's after him in particular. Or some sort of information he has, maybe the Irish? That Clay is behind it seems most likely, but I'm hoping the show surprises us with a curveball here.
As far as Opie's motivation, I can't tell just yet. I'd like to think his move was one of solidarity and he intends to remain at Jax's right hand, but Opie's always been a hard character to predict. However comma, he's never really been a schemer and is more likely to just confront something head-on (like he did with Clay), so I don't see this being part of some long con. If it isn't, and he's being legit, I hope they keep him that way. There's nothing quite as exasperating as a wishy-washy character in fiction, and despite how cool Opie is his moodiness has him verging on that territory. I don't think the fact that he shot Clay will go over well with the ferociously loyal Tig, and I predict there's gonna be some friction there in the near future.
That conversation Clay had with Opie seemed like the seed of something, perhaps Clay trying to regain some lost ground by putting out feelers. Maybe he's looking to sew dissent within the ranks? Opie's a polarizing figure now to most people besides Jax, what with his shooting Clay and his occasionally questionable commitment to the club, so pushing him back to Jax's side is actually kinda brilliant. Anyone who has reservations about Opie (like Tig, probably the new pledges, maybe even Bobby Elvis) will automatically associate those misgivings with Jax when the President shows loyalty to his friend.
I don't know about Nero at the moment. He's cool as fuck and I'm enjoying the hell out of Smits' work so far, but he won't remain peripheral for very long I don't think. He doesn't seem to be up to anything, but I can definitely see it going either way if he's presented with an opportunity to benefit at the expense of Samcro. He might become an enemy, he might become a valuable asset, there's really no telling yet. But I'm looking forward to finding out.