Coffee from a dedicated Starbuck kiosk is not (very few ships have those) but most ships have or are converting to serving Starbucks at all their other coffee venues which you can get.
The D drink perk is like having a 4 drink alcohol package, with the limitation that it can't be used at the Bionic bar - any drink from any venue covered by the drink package under the drink package limit ($14 now days) can be had with the D drink voucher.
Some sailings in different markets may have a different price since includes grats, but the underlying price and what kind of drinks it covers should be the same fleetwide.
Working by the window in the library usually has a decent wifi connection and is fairly quiet, most of the time.
Biker, who would recommend breaking up a long post like that into more manageable chunks.
Those or best to go to the venue and book there as they may have times not listed in the app and they can confirm that the perk is in their system (sometimes it's not).
I don't believe there are any cabins on any current ship in the fleet with "windows" that open.
Biker, who is waiting for someone to chime in with the exception.