Welcome. In general, as my last physics course was back in the day, a 220v charges up to 5x faster. If you are saying you will be charging overnight, you are right that a solid 10 hour charge will restore around 40% of the battery. If you are in warm climate area, 40% will get you over 40 mile roundtrip. So you can top up every night with your existing convenient outlet. I can't comment on 15 v 20 amp but you can search this forum for topics on charging.
It is generally not advised to use a long cord to charge using 220v given a concern about overheating the cord or outlet. I figure one hour gets me 25% of my charge back, so only four hours to get 100% back.
Hope this helps directionally if not specifically.
Enjoy the ride Vic.
Jeff in NYC
MB '17 B250e; MB '06 E500W; MB '81 380SL