I could be wrong but I think it is illegal to cut cypress knees. But that may apply to wild areas and not residential areas. Doesn't matter though because they will keep coming back if there is a tree nearby
Drill a hole in each of them and pour in some round-up. That'll take care of the knees...and probably the tree
Roundup works by moving through the leaves of plant life. You would need to spray the needles on a Cyprus.
The sawzall is good practice for firing full autos