A wonderful overview...and thank you for the links for further reading!

A clarification on this...

"Every 4 years the difficulty level for these mathematical equations increases, in fact, it doubles."

• Every 4 years the block reward halves.
• Every 2 weeks the the difficulty changes -- it can become either more difficult or less difficult, depending on how fast the network is solving the blocks. The goal is to add a block every 10 minutes.