So according to your research "ROSJA.627" means 627th Rifle Regiment? And what about 627th Rifle Division?
I see the a Russian wiki page about this division:
Also more generally, what was life like between the Soviet occupation between 17.9.1939 and 22.6.1941 (Barbarosa)?
It was a very difficult time for Poles living in the city. From the east came the Russians. They were like a wild barbarians, the lacked any manners, their behavior caused a widespread disgust. Residents alternately lost and gained hope, in the light of developments on the fronts of war. There followed a number of displacement actions, deportations, mass arrests, all this heightened fear to the extreme limits.
In March of 1940 in one of the reports has been written:"People - especially the Poles - are already pushed to their limits. The continuous fear of deportation, revisions, removal from homes, constant cold and hunger, arrests, all of this has led some to a state of complete numbness and apathy - the other to a state of savagery."
In the summer months of 1940 the mood of Poles was so characterized:"The great depression. The people who consider themselves Polish, is expecting longed changes. They vegetate rather than live - in theaters, cinemas, you don't meet anybody, no chats in pastry shops. Partially working hard for a piece of bread, and in many cases, being without a job use the remains of former prosperity, and even the one who works, also partly sells everything. There are also those who seek comfort in vodka, which is in abundance - they are usually lost.."
Source: Grzegorz Hryciuk - "Poles in Lviv 1939-1944"
Would the Polytechnic still have held classes?
Yes, Lwow Polytechnic was still active, although in 1941 it lost twenty five Polish professors - who was murdered by German occupiers. Still in April 1945 in this Polytechnic were employed 204 Poles (of 272 total employees)