Q 1 - The "why" on this stuff has not been made public, and will not be made public. But the tip of the iceberg looks like Lori was either acting/speaking loony tunes, or out-of-her-mind depression, or schizo-based loss of reality, and she couldn't interact with defense counsel to prep for trial. It took them about 10 months to bring her back to "normal."
Then, 6 months later, it happened again. Why? We don't and won't be told. But by appearances we should probably call it a relapse. The DP issue may have played a role, but who knows.
My personal opinion is that anyone who is so self-absorbed and narcissistic that they see themself as a goddess is going to have a hard time when facing a trial that says they are wrong. Because, they CAN'T be wrong. Yet here they are. Now what do they do?
Q2 - In contrast, the removal of the DP was logical, and transparent. It happened because the Prosecution team kept working as if they had forever to provide disclosure to the defense and have a trial. But they didn't, because LVD did not (and would not) waive her right to a speedy trial. Eventually Boyce set a trial date for Apr 3 - period - and a drop dead date for ALL disclosure by _______ (I don't recall exact date, but maybe Feb 26?). Which, stupidly, the Prosecution went past. Some of it wasn't a real big deal, but some may have been. Anyhow, in essence they did a big evidence drop on AND after the deadline.
Boyce ultimately ruled that (a) he couldn't delay the trial, to give the defense the time needed to prep for the new evidence, because in doing so he would then have to dismiss the case due to speedy trial violation, and such a dismissal is unfair to justice for the victims, so (b) he removed the DP possibility, which then would save the defense from having to prep all the new evidence for the DP issue too, which would have taken place in a 2nd or mini- trial after, if she was found guilty. In that way, he was giving them extra time for prep, so to speak.
TL/DR version - The DP was dropped because the Prosecution team was sloppy and wouldn't meet the necessary deadlines.