Regarding your question about eternal spiritual and temporary spiritual, the temporary spiritual is the impersonal brahma-jyotir. The impersonalists by severe austerities and penances arise to the Brahman effulgence. But it is only temporary. Eternally we cannot remain aloof. As living entities, we want pleasure in association; therefore we see in the material world where for sense gratification the karmis take so much responsibility. First of all they accept one wife. The more he enjoys the wife, the more he becomes implicated. So, this means that we must have pleasure even at the risk of gross implication. Therefore our Krishna Consciousness movement is that we want pleasure but without any implication. This is happening actually. All of our Krishna Consciousness students they are enjoying life without any implication.
The impersonalist who prefers to merge with the Brahman effulgence has no shelter at the lotus feet of Krishna. Therefore such impersonalist even though raised to the Brahman platform come down again to the material world for pleasure's sake. In India you will find many sannyasis who merge into the Brahma effulgence, but without any pleasure there, they come down to the platform of material activities of opening schools and hospitals—Daridra Narayana, etc. Such men with poor fund of knowledge do not know that in the material world however you try to arrange things very right, it will always fail. But in the spiritual world the spiritual varieties displayed by Krishna along with his associates gives eternal pleasure. That is wanted. The Brahma effulgence, there the pleasure is temporary.