I'm confused about electoral votes.

Ok, so I know that when you cast a vote for a candidate on Election Day, you are actually endorsing the elector who would then cast his electoral vote for that candidate. I know that there are specific numbers of electors allocated to each state, depending on the number of representatives of that state in congress, which is in turn partly dependent on the state's population.
The thing is, since electors are chosen or nominated by each state prior to Election Day, and each one is pledged to vote for a particular candidate, how does that come into play on Election Day?
For example, California has 55 electoral votes. Say 25 electors have pledged to vote for Candidate A, 20 for Candidate B and 10 for Candidate C. Wouldn't that mean that on Election Day, even if the majority of the population (say, 55%) voted for Candidate B, only 20 electors are able to vote for him, so Candidate A wins because PRIOR to the real election 25 electors have already confirmed that they would cast their vote for Candidate A. Why even have an election? Why not just an election for electors? How does this work?
I'm also quite sure that it works by a winner-takes-all system where the candidate with the highest votes but not necessarily the absolute majority of the votes ends up getting all the electoral votes of that state, and then the winning candidate has to get the majority and not just the highest number of votes of all electoral votes in the nation. How do actual votes translate to electoral votes? Sorry it's such a longwinded question it's just been bugging me for a quite a while.