An ‘Interstellar’ Explainer: What Are Bulk Beings?

It seems implied that the bulk beings are the descendants of the humans on earth. That said, if we are going to have an Interstellar discussion, there are two things that confuse me about the film. Specifically:

(1) What exact role is faith supposed to play in the film? The underlying message of the movie seems to be that our human struggle to overcome mortality can be a redeeming force that makes mankind divine so long as the scientific effort is guided by love (when guided by egoism or war it becomes unpredictable and destructive). But then there is an awful lot of dialogue about Murph having faith and Tom NOT having faith and Cooper is clearly a Christ figure. So what role does Nolan intend faith to play? Is the film really secular in its message (there is no God but man), or is all of the Christ imagery a metaphor for how the love of God/Christ is hypothesized to actually work, with God as the pearl in the oyster beyond the realm of scientific perception? And if there is supposed to be a God how do we reconcile that with the narrative-level metaphor of the journey into the cosmos as a quest in search of a God who is not there (Wizard of Oz, 2001, etc.).

(2) Mann's view of love is selfish. Brand sees love as a divine cosmic force. And Cooper sees it from the perspective of social utility ("child rearing"), which interestingly mirrors his attitude to the flying drone at the start of Interstellar, where Cooper talks about giving it something "socially responsible" to do. I am confused if the film criticizes Cooper's values and praises Brand's, or whether Cooper is the positive figure who walks a line between the two extremes of selfishness and selflessness....

Interstellar Animated and Abridged (SPOILERS) : http://youtu.be/_2UTU2dE4hE