Is an ISO for offline update available at all? Microsoft surely makes it hard to find.
In the meantime, you can download the online installer [1] and run
vs2015.2.exe /Layout
Use the menu on the left of the page and select ISO.
Then again... I only have an MSDN subscription because my previous job STILL hasn't removed me from their lists. Not that I expect them to with the clowns they replaced my previous company with.
Very nice perk to still have.
Supposedly it should contain Visual Studio too, but I cannot see the isos on the download page. R Studio for Redhat and SuSE, on the other hand... ;)
Other odds and ends...
Note that you can only claim a limited number of keys per day. So don't get carried away claiming all five keys on one product, then all five on the next, etc. You will soon hit your daily limit. Spread your claims out among the products you think you might need until you run out, and then come back the next day to claim more.