Retirement tax questions

I know that basic fact, the question is how to take advantage of it.

 

For example, I think that if I declare at FRA (age 67), I can collect 50% of my wife's benefit, then declare for myself at age 70 and collect my own benefit (which will be less than my ex's full benefit but more than 50% of her benefit)?   Then, can I/should I continue to work to bump up my earnings history?  What other options are there, and what mistakes do I need to avoid. 

 

[Edited to add]

This strategy is no longer allowed.

https://www.ssa.gov/benefits/retirement/planner/claiming.html