The Attorney General will be picked by former AG Alberto Gonzales' Chief of Staff who later went to work for Giuliani's law firm, Bracewell & Giuliani. Now he is with a company that manages the personal wealth of billionaire Steven Cohen. Cohen was recently in the news when he lambasted the lack of U.S. hedge fund talent and opened a training academy overseas to train young analysts from Asia and Europe. So much for bringing jobs to the U.S. (His former hedge fund pleaded guilty to insider trading, and he can't recruit directly before 2018 due to his personal settlement agreement with the SEC, but his company has been able to hire all of the foreign analysts who attened its training academy. Or something like that, read the article.

For social security:

Michael Korbey was a senior adviser to the Social Security Administration under the tenure of President George W. Bush. He helped spearhead a public campaign to rally support behind privatizing Social Security. Before that, he worked for the lobbyist group United Seniors Association.

The EPA:

Myron Ebell is the director of the Center for Energy and Environment at the Competitive Enterprise Institute. Sometimes called a climate "denier-in-chief," he has long had ties to the fossil fuel industry. Ebell has called for abolition of the EPA and wants to scrap the Paris climate treaty, a deal Trump has vowed to withdraw from.

About why Chris Christie got marginalized: There are several reports saying Jared Kushner wanted him out. Why would Kushner want him out? Maybe because Christie prosecuted his (Democrat) father who went to prison a decade ago.

[Edited/Added: I don't think Christie's exit was due to Kushner. I have a new theory based