I am new to these cars and found a 2010 MKS with bad engine (no info on what is wrong). I was thinking in worst case I can buy a used engine from yard and have a shop install it. How involved is swapping engines in these cars? 
Is the ecoboost in the F150 compatible or are they body specific?

Thanks

Welcome and sorry to hear vwhat happened, if I may ask?

Would try to get an engine from a 2013 up sho mks flex etc.  will have to swap over a few parts from the 2010, nothing major.  Prefer engines with composite valve covers (redesigned to address oil consumption issues) but not necessary.  Do water pump, timing chains, tensioners and guides along with vct solenoids on the "new" engine. Maybe even an lms oil pump

Labor time not sure what the book calls for, but I expect engine pull and install to be no more than 16 hours work.  Mostly just a lot of steps.

F150 engines are laid out differently and wont physically fit.  The engine management is different as well, but not sure how much of a hurdle for a talented tuner.

I don't know what happened to the engine it is at an auction and they don't give many details. I wanted to get it cheap enough to make it worth my while and learn about the drivetrain in the process.

Thanks for the info didn't know about the changes throughout the years for the engine.

Sure thing!  Post questions as you move forward!