If Krishna is self-sufficient then why did He create us? Is it to serve Him?
Yes, Krishna is self-sufficient, however we are not self-sufficient. He is perfect, however we are not. He is self-satisfied, however we are not. He is completely independent, however we depend on Him. It was our desire to be separate from the Lord, therefore He has created this material world. He never created us. Both the Supreme Lord and the living entities eternally exist. Only thing is that we forget, however He never forgets us. He wants us to come back to Him as quickly as possible. He doesn’t like His children to be suffering in this material world in forgetfulness of Him.
Just like father feels happy when the child offers him a flower or a small gift on his birthday. Similarly, Supreme Lord feels happy, when someone makes a small gesture of service toward Him. We have not realized how much pleasure is there in serving Him. We are trying to serve family, nation, community and many others, however we are not satisfied at all by serving them. Because all of them are like leaves of the tree. A tree can not be nourished by pouring water on the different branches, fruits or leaves of the tree. However, when someone waters at the root of the tree, all the leaves, branches and fruits are properly nourished. Supreme Lord Krishna is the root cause of everything. Many devotees in the past have served Lord Krishna and achieved perfection of their lives. Therefore, it is better and safer to serve Krishna than to serve material agents and prolong our existence in this material world.
What sort of heart and qualification required to completely surrender to a spiritual master?
Krishna describes in Bhagavad Gita how one should approach a realized spiritual master (Bg 4.34). He indicates three components: submission, inquiry and service. One should approach the spiritual master with all humility, hear from him submissively and inquire from him to get a clear understanding about the spiritual science. Inquiring alone is not sufficient, but one must also render service to the spiritual master according to what one has heard and try to please him. One should be prepared to render menial service to the spiritual master and follow his instructions.
If one is very sincere to know Krishna, He will send His mercy in the form of a representative, to provide exactly the kind of spiritual upliftment the soul requires.
How activities in Krishna consciousness can lead one ultimately to the spiritual goal is described here. There are various activities in Krishna consciousness, and all of them will be described in the following verses. But, for the present, just the principle of Krishna consciousness is described. A conditioned soul, entangled in material contamination, is sure to act in the material atmosphere, and yet he has to get out of such an environment. The process by which the conditioned soul can get out of the material atmosphere is Krishna consciousness. For example, a patient who is suffering from a disorder of the bowels due to overindulgence in milk products is cured by another milk product, namely curds. The materially absorbed conditioned soul can be cured by Krishna consciousness as set forth here in the Gita. This process is generally known as yajna, or activities (sacrifices) simply meant for the satisfaction of Vishnu, or Krishna.
Every endeavor requires land, capital, organization and labor. Just as in business one requires a place to stay, some capital to use, some labor and some organization to expand, so the same is required in the service of Krishna. The only difference is that in materialism one works for sense gratification. The same work, however, can be performed for the satisfaction of Krishna, and that is spiritual activity. If one has sufficient money, he can help in building an office or temple for propagating Krishna consciousness. Or he can help with publications. There are various fields of activity, and one should be interested in such activities. If one cannot sacrifice the results of his activities, the same person can still sacrifice some percentage to propagate Krishna consciousness. This voluntary service to the cause of Krishna consciousness will help one to rise to a higher state of love for God, whereupon one becomes perfect.