Old age
Of course. The pope is a human being and, as with all humans, popes die.
yes, unfortunately there were some popes who were morally corrupt. but not in matters of faith and doctrine.Yes, definitely. As an example, do some reading on "Inquisition", which was carried out by the Catholic Church, under several popes.
Yes, they had many differences on matters of authority and doctrine. Some Popes were even excommunicated by Church Synods (or Councils) and other rival Popes were elected in their place, called Ante-Popes.
There are lists of the popes available. However, there is some confusion with some of the earliest popes and their positions on the list. No official record of their papacies remain and historians can only make an educated guess as to what sequence is correct.
Popes do not elect popes. Popes are elected by the cardinal electors.
The Church has had some very bad and evil men as popes in the Church's long history. Other have been good men but did nothing deserving of sainthood. Others led saintly lives and were canonized.
Please specify which of the 266 popes you are referring to. 264 of them have died (as on January 2015).
There have been 8 Catholic popes named Alexander. Please be specific.
There have been 3 popes named Julius. Please specify one of them.
Nearly all popes die during their papacy since the position is for life. A few, very few, have resigned but the vast majority died in office.
There have been about 80 popes who are considered as saints. Some of these were declared saints in the early Church before the canonization process existed. Others are in various stages of canonization. See the complete list of popes and you will find all the popes who are saints, canonized saints and candidates for sainthood.
The vast majority of popes have been Italian. As of February of 2013 there have been only 18 popes from other countries.