Aside from making the phone thinner, fusing the display and digitizer eliminates the issue of dust infiltration (specks of crap under the glass that just can't be cleaned off) which is a warranty/service concern on devices where the two are separate. The combination is also more rigid, providing a subjectively better (firmer) "feel" when the user taps the screen. It's also, all else equal, more resilient against impact or drop damage. From an engineering standpoint, the case can easily be made that these advantages outweigh the potentially increased repair cost, especially since the fused glass is less likely to break to begin with.

Looking at the pic in step 6, it would appear the two data pins are shorted together, tied to +5V via a 75k-ohm resistor, and tied to ground via a 45k-ohm resistor. The resultant voltage divider should hold the two data pins at about +2V. As the data pins have 0V between them, any remotely modern cell phone will recognize this as a charger. An Apple device would recognize this as a 500ma charger, and most recent Android devices mimic Apple's scheme for identifying chargers.

The de-rated capacitors were likely deemed sufficient to regulate the ripple at 500ma. Such cost-cutting (and exaggerated specs) is par for the course with products manufactured and designed in China. My experience is that these things reliably (but slowly) charge my iPhone, and I can get them at the Dollar Tree.

It's been my experience these things work reliably with my Apple devices,