I agree that it doesn't seem too healthy to get a puppy that was dropped off at someones house....

Anyway...

I don't know if this is any help, but here is everything I knew about boxers and owning them before I got Jasper, hopefully you will know everything here about labs.(Also I researched for about a year and a half)
I knew.....
-Their temperment
-Their personality
-Their exercise needs
-Their cost(vet, food, neutering..etc) per month
-Their possible health conditions/things they are prone to
-How big they get
-Best food for them(boxers will not "tolerate" much corn in their food)
-All about socializing
-About crate training
-Knew about GOOD dog food
-And talked to tons of boxer owners about how raising a boxer is and for advice.

AND I also searched alot to make sure I got him from a very responsible breeder, and asked her tons of questions about her experience and about his parents, and he even came from a different province, but it seemed she was most responsible.

Just some tips, hope you know most of that