Some tough questions there.
I'm not sure how much I believe in karma. I tend to think about it more in terms of "the universe reflects back to you what you put out into it".
I also think that what we project out tends to follow us into the next life, at least to some degree.
I think the concept of God depends entirely on who you ask. I believe in the Force, at least that's the name that I give it. The Japanese call it Ki. The energy that underpins everything in this reality, the energy of life, the Force.