From what I understand, 处士 can mean both not taking office or living away from court between appointments -- and the commentaries I checked claimed the latter. It's possible he's the 8th Wei son of his generation, but every other poem I've seen, unless it's addressing an extended family member, it's meant his highest rank as an official. Not conclusive, given my small experience, and I should see if I can confirm that here.

It doesn't sound, from Du Fu's biography, that he was back home in Luoyang during that period. (I did almost note in the notes that he wrote this shortly after failing a couple times to keep office himself.) But 20 years before, he was still living at home, so maybe he did visit. Hadn't thought of that. And yeah, it will be literal mountains -- Du Fu will soon (if he hasn't already) be moving to Gansu and then south to Sichuan.

As for texting, I keep coming back to this one.