Don't care what rulebook is used here.

Runner at 1st is off on the pitch and runs into the 2nd baseperson just as the batter pops up the pitch to 1st. Easy double-play.

Now, we had obstruction on the steal. What is the call? What rule?

Out at first since the OBS was not while returning to tag. This is one of the exceptions to the "cannot be called out between the two bases where the obstructions occurs" part of the OBS rule.

In ASA, the rule is 8-5-B-1-b, Other exceptions to this rule are a missed base appeal, an act of interference, and passing another runner.

Speaking ASA

If the umpire judged that the runner which left the base too soon would not have made it back to 1B even had their been no obstruction, and the defense properly executed a live ball appeal, the runner is out.

Before you all jump on this, go read POE #36 which covers this specific scenario.

This one shouldn't even be an issue. If the OBS occurred while the runner was moving away from 1B, then the advantage goes to the runner as there would be a shorter distance to return to 1B. IOW if the OBS had not occured, it would have been more difficult for the runner to get back to 1B.