Has there been any rumour of whether 095 or 096 is likelier to begin construction first?
095 SSN. The PLAN does have urgent need for newer SSNs more than SSBNs at present (and because China's nuclear arsenal is still mainly land-based).
Also it would seem weird to me for a random stern section to be placed outside.. wouldn't it be assembled inside the hall?
It is common for individual sections/modules of submarines to be assembled in other hall(s) before getting moved into the main assembly hall (the ones with rails extending from inside the hall) for overall/final assembly of the entire boat.
The stern section of either another 093B or the 1st 095 that we saw in that satellite photograph could be in the process of being moved. Nothing wrong with that.
Doing A-to-Z assemblies for such massive boat inside one hall would be too cramped.