#1. Is the WWE brand split over or can certain stars go wherever they want?
The brand split was put into place on WWE television so that RAW and SmackDown would be seen as their own entities once again. The only exception was the strange "wild card rule" and the Women's Tag Team Champions, who are allowed to compete on all three brands.
That being said, there seem to be several exceptions to the rule. WWE fans saw last night on RAW when King Corbin was allowed to make an appearance on the Red brand despite being a SmackDown superstar.
Corbin accepted Bobby Lashley's offer to dismantle Drew McIntyre before WrestleMania and get a WWE title shot in return. If Corbin becomes a mainstay on RAW, then the brand split's relevancy will certainly be questioned by the WWE Universe.
Perhaps MVP could make a deal to keep Corbin on RAW and avoid this plothole, but it would mean there are ways to manipulate the brand split whenever it suits the ongoing plot.
Instead, WWE could have given Corbin's spot to a deserving undercard talent from RAW. This wouldn't have created any confusion regarding the brand split in the first place.