Standard, toss-up, though I would still lean Richard. I would think the Muscle Hamster (Martin) gets the meaningful running down carries, but not sure he's impressed a lot in his carries so far, and the Raiders are a team that will definitely be passing a lot. Richard is more dynamic of a runner as well.
The state of their O-line is in shambles with injury and general lackluster play, so Martin may not have the same success as Lynch did, given that Lynch's ability to make something out of nothing is pretty unparalleled.
From what I can find, anyone put on IR can be activated later in the year. There's a max of 2 players per team allowed to come back, but teams no longer have to declare the "return" designation when they put a player on IR. Players must stay on IR for at least 8 weeks before they can return.
So I think they COULD bring him back starting in week 9 (assuming he's healthy).
I've got him stashed in one league so from a selfish perspective it would be nice to see something from him this year to set his keeper/trade value for the offseason.