There are (or at least were) actually competent engineers at spacex. While we can't rule out overengineering to an obscene degree, the amount of propulsion is going to be very limited. Basically enough to make minor adjustments and then one last burn to "safely" land.

Which is basically comparable to wind carrying a conventional booster off course. Yes, it is possible but it is mitigated by landing in an ocean and not doing this on windy days.

No, The issue is that there was a failure. Doesn't matter when or where it happens. Something that was supposed to work didn't and we need to understand that before we have yet another Challenger.

Let's put it this way (yay metaphors, these never leave to pedantism and derailment): You just got home from driving to the local fun fair. You close your door and your mirror falls off. It happened AFTER you drove and AFTER you turned off the engine but... are you going to go on any road trips before figuring out what the hell happened?

If I remember correctly, they steer the rocket a little off from the landing spot until the last second so if anything were to go wrong it crashes in a safe, predetermined spot.