Popular vote vs Electoral College

I went back and read my earlier post on voting for the President of the United States, and am pleased to report that I understand the whole process more... So I'll try to explain better now. I wanted to do this post last November, because there was so much press about President Trump winning the Electoral College but not the popular vote (only the fifth time in USA history this has happened). but you know, babies, Christmas...

In the second presidential vote (the first being just so the two main parties can chose their candidate), each state has an election. And they vote either for one candidate or the other BUT, there is often an opportunity to 'write in' a candidate (ie, Colin Powell) or vote for an independant. If one candidate gets most (not even 51%) of the vote, they win (first past the post?), and get the Electoral College votes for that state (generally).

The Electoral College are people. I don't know how they're chosen. but they then go to some sort of third round of voting and formally vote for the candidate that their state has chosen. Some states divvy up the Electoral College votes, but most, as far as I can see, most states just give them all to the person who got 51%.

Faithless Electors - are Electoral College members who go against what their state has told them to do, which they can, but it would possibly be a bit like a Liberal candidate in Australia being elected and then turning around and supporting the Labor party in parliament (?). There were about seven Faithless Electors this election. 

So, it is a bit like University - you want to do enough work to pass, but the rest is icing (or marks towards honours, depending on your point of view). Hillary Clinton won the popular vote because in states where she won the Electoral College vote, she won about 80-90% of the vote - ie, heavily blue states. Donald Trump on the other hand, won more 'swing' states, but the vote was more even in many of those states.
For example - Pennsylvania:
Trump - 48.6% (2,970,733)
Clinton - 47.9% (2,926,441)
Johnson - 2.4% (146,715)
Stein - 0.8% (49,941)
(http://www.cnn.com/election/results/president)
President Trump won the electoral college votes (20 of them) in this state by 44,292 votes.

Overall, Hilary Clinton won 48.5% of the total votes, while President Trump won only 46.4% of the votes, but he got the required Electoral college votes to win the election overall.

Swing states (purple states) - If you colour in the map of America according to how they habitually vote - red (Republican) or blue (democratic), there are only a certain amount of states that have a regular close election that could go either way (Colorado, Florida, Iowa, Michigan, Minnesota, Ohio, Nevada, New Hampshire, North Carolina, Pennsylvania, Virginia and Wisconsin according to one website), which drastically reduces the states that get serious political attention paid to them.