I'm pretty sure it's Shen Wei's office, because it looks a lot like the office Shen Wei has in prior episodes, but it could also be that all the offices are identical due to the architecht just planning it that way (the heathen).

One of my favorite bits of Shen Wei and Zhao Yunlan's relationship is that they both wear masks – Shen Wei's are on occasion literal as well as figurative. He puts on the role of Envoy, he puts on the role of Professor, and the real person is somewhere behind it all. (I have long and involved theories about how everyone is but a collection of masks we wear in different contexts, all the way down like an onion, but Shen Wei and Zhao Yunlan are very good at wearing masks.)

I wonder if that's because he, too, can see the SID's attitude about Dixingren has changed? (I mean, for one, it's hard to notice that change if there aren't any cases where that might become obvious, and also, I do think there's a noticeable change even over the course of the first several episodes.)
DAMN I didn't even think of that. Yeah, that's ... depressingly plausible. And the SID being a terrible working environment for Dixingians would explain why Chu Shuzhi wasn't present for the popcorn scene, why he's so grumpy and standoffish, why he's such a colossal Envoy fanboy (he's doing this for the Envoy, so to make the pain lesser, he'll just put the Envoy on a greater and greater pedestal to justify it all), and it's all so very depressing. Of course he'd be relieved when his boss starts seeing him as a human.

Btw, the heels on Shen Wei’s black shoes (and most of the shoes he's been wearing) look perfectly normal to me for that kind of men's style? Not remarkable at all, unlike the ones in episode 1.
This might depend on the region, but from my observations the heels on his shoes are on the taller end of normal here. He does own shoes with more heel on them, though, even leaving out the ones from episode 1.