Sonically and thematically the transition between G.U.Y and DWUW works fine. It's also a strategic move to put them first as G.U.Y would gain familiarity for later single release and both it and DWUW would convince those listening that the album is a stronger pop album than it is. Beginning with Aura and Venus did the opposite for ARTPOP.
MJH/BDKMV/Swine/Dope are thematically linked. Simply put; she sings about smoking weed, she sings about being high, she sings about struggle/despair, then she sings about redemption. Whilst Swine is actually about something else, without backstory and in this context it makes sense to someone at face value.
BDKMV was included because it does "urban" far better than JnD did and far more authentically for Gaga. It's still pop and Gaga, but in a fresh and different way.
The transition after Dope is going to be messy no matter what because it sticks out. Fortunately, you can sonically fake a smoother transition with the beginning of Fashion! having a piano intro after the piano-led Dope. It also lifts the mood to transition into the upbeat, fun final run of tracks.
And again, strategically speaking, BDKMV would have been far more beneficial inclusion than JnD, and if you want to maintain a casual listeners interest throughout an album - you have to spread out the highs, lows, catchy and intense so they don't stop. It's also key to convince the albums quality. Having lulls or too much of one thing in a row ****s things up.
As for singles, DWUW was probably the best second single. What happened to it was unfortunate but not its fault. Had it not featured R Kelly and had someone like Drake for instance, it would have smashed.
