2) You run it on farm rig. What a farm rig looks like? It's a computer with minimal software installed, usually it's windows, some gpu monitoring/tweaking software like MSI Afterburner and alike, and miner-software. Rig owners doesn't store anything valuable there and also have some acronis/etc backup of whole ssd/hdd from that rig and can restore it in 10 minutes.
Is it going to steal your wallets/passwords/etc? See 1) and 2).
Nothing personal here, and I'm not gonna judge you for something rather than thank for this miner. Butttt... You're wrong here. At least half of newbie miners have 1-2 cards, which may even (ouuuch!) put w/o risers into closed standard midi-tower case. And that's the only PC they got. So, gaming daily, sleeping+mining nightly. Are you sure they got backups and lack personal data on their drives? So why are you surprised that someone got bored when he saw "blah-blah-WannaCry" associated to your file, bro?

That's normal, they don't wanna cry. Uh oh, yeah you can use sandboxie and/or other techniques to isolate suspicious executable, but u need some skill for that.