Christopher,
1. Using an iPad mini Retina (a.k.a. iPad mini 2), I too get only 4-note polyphony. Curiously, on the Main edit page under “AMP,” touching “All Voices” pops up a window with 8 pan pots; the left 4 do what you’d expect, the right 4 do nothing. I noticed also there is no double/split mode.
2. The first 32 waveforms were used for user-defined waveforms on the VS. The user would select, set the harmonics, and mix 4 waveforms—including ones which were user-created, if I remember correctly—and save them to one of the first 32 slots. No idea why this wasn’t implemented.
3. The original had no oscillator sync. My only guess as to what LFO sync might be is for syncing it to an external clock. (?)
4. Google “Prophet VS manual” to find the original manual in .pdf. It might be helpful if you’re unfamiliar with the VS.
5. You didn’t ask, but next to “Master” and “Bend Range” above the wheels is a little keyboard icon that, when touched, opens up some other options, one of which is “Voices.” The VS would use “Circular” when in poly mode. You’d normally want this with longer release times and are expecting notes to overlap. (This one got me for a couple minutes until I found it.)