To understand Krisna in His highest manifestation as Vraja Krisna is very difficult, even though it may seem to be easy for us, and "Srimad-Bhagavatam" is purifying our heart to give us this experience – Krisna’s darsan.
The second part of the Seventh Canto is describing varnasrama. Following varnasrama dharma without being a devotee is useless because it will not bring you to the ultimate goal of life. The purpose of all the rules and regulations is to please the Lord, as a result we ourselves and all the people around us will be satisfied.
Bhakti is available to everyone, you don't need a preliminary qualification. The only qualification for this is faith, and anyone can develop it. A direct way to develop pure devotion is to come in contact with the pure devotee, open your heart, listen with faith and serve him. The essence of the second part of the Seventh Canto is to understand how by following the duty of varnasrama one prepares one’s heart for bhakti and how one becomes receptive to bhakti.
The essence of varnasrama system is to help people to get purified from material desires. And after that they will very easily develop sraddha in the process of bhakti and will start worshipping the Lord, and the Lord will start reciprocating with them.