Last question first - there is a difference between the U.S. Ball applesauce recipe and the Canadian Bernardin applesauce recipe. The Ball recipe does not call for lemon juice the Bernardin recipe does. Generally apples are acidic enough not to require lemon juice but Bernardin takes the more conservative approach in that windfall apples or bruised apples are less acidic. I wouldn't worry about your recipe and wouldn't re-can but in future if your apples are damaged in some way you may feel more comfortable with the lemon juice addition.

Your jars leaked either because your applesauce was too thick or there wasn't enough headspace. Or both. It expanded. As long as the seal is good it's fine but next time be careful to check density and headspace.

Carol

That or you did not let the jars sit in the canner the additional required 5 min. after processing and removing the lid before you take out the jars.