Question

Which part of the Declaration of Independence acts as an implied plan of action, in that it lists laws and practices to be changed?

Answer 1

It would be the "the preamble" that implies a plan of action and lists certain things to be changed, since the introduction is far more general in exclaiming why in fact they are claiming independence. 

Answer 2

"When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation."