Hello, V1,
I've tech stopped and overnighted at UHPP. It is probably the most used airport in eastern Russia, very popular with bizjets that need the fuel stop. Handling was fine. You will need de-icing, I was there in late April and it snowed every night. Drive to town is about 25 minutes. Two hotels, the Avacha and the Hotel Petropavlovsk, not much to choose between them from our office's experiences. The Avacha is nearer the town center, if that matters. It has a restaurant and a Mickey D's across the street. Lots of high terrain, so plan out the arrival and departure carefully. Aeroflot transits daily from Moscow, so airport is maintained, but the runway will rattle your teeth. Petro is a navy town, you'll lots of uniformed kids.
Internet may not be available, we have had to rely on texting.
Haven't been to Vlad, but it is a major airport, I suspect no problems. Anadyr might be difficult, not widely used.
Don't plan on a hangar at UHPP. Alternates are a long distance away at all of these places. Magadan, Sakalin and Khabarovsk are usable, Khabarovsk is right on the Chinese border, so might not work for you.
Are you familiar with Russian ATC procedures? They might still be using QFE, ATC expects a "gear down" call prior to landing (yes, even if bolted down), you might get a vector at 90 degrees to the ILS and left to your own to intercept. Your ATC airways "clearance" will be nothing but a squawk code and a departure route, everything else is assumed to be your filed route.
Flight planning: be vigilant about entry and exit points, they can be sticky about this issue and they might restrict your routing.