a)got booted out of Iran
The US had always supported the Shah with money and other things, because he was our friend in the middle east.
b)how Carter helped it happen
He pulled all money and military support from the Shah
c)what is a “shah” and how was he a good guy. That title sounds like royalty, some sort of elitest. Hardly an elected kind of thing although I understand that rulers born to the job can be America’s friend.
For the middle east he was a benevolent ruler. Women were treated as equals. They wore western dress and could drive. Yes, there were some who didn't like him. (Think the Osama Bin laden types). The Iranian people lived in a modern country. All that ended when the Ayotollah took over. The beheading began. Women were arrested for how they dressed and had to start wearing the head covering to survive.
The real question here, is why was the Shah treated in such a way by Carter, who now wants to talk to the current ruler, who keeps his people isolated and living a very deprived lifestyle. Women are treated worse than slaves were once treated in the US by Jimmah's ancestors.
Here are a couple of articles that will help clarify your questions.
“Shah” really designates a dynastic ruler or a King.
The late Shah was decreed a Shahanshah or Emperor, which in the old days meant he would have had other kings as vassals. He was granted the historcial mantle
In fact Persia was the only country to ever capture a Roman Emperor.
The late Shah’s father, Reza Shah was so fed up with a weak and ineffective Qajar dynasty, whose teenage Shah lived mostly in Paris (Mossadegh was a prominent member of that family and wanted to restore the Qajar dynasty rather than all the altruistic labels attached to him as a nationalist) that Reza Shah wanted to form a Republic and take over as an elected President!!!
The Members of the Iranian Parliament and Senate - energetically supported by the Islamic clergy - absolutely refused and told him he HAD TO take over as the Shah and voted him into power as a Shah. After which he put back a country that had splintered into tribal territorial self-ruled components without any central government control - into one where the Central Government again took charge.
Albeit subject to the influential interference of both the British and Russians, who continued to call the shots till he began to stand up to them.
Luckily he commanded the Cossack Brigades of Iran and had one of the best local fighting forces who were loyal to him and gave him a bit of sting when he demanded something from the British and Russians.
http://noiri.blogspot.com/2004/03/jimmy-carters-illegal-demands-on-shah.html
http://noiri.blogspot.com/2004/03/who-is-ayatollah-khomeini.html
Also check out the food crisis in Iran (and video)
http://noiri.blogspot.com/2008/05/ever-fewer-iranians-can-afford-to-buy.html