It largely depends on how you define God.  The traditional monotheistic interpretation of God is as a singular, masculine consciousness.  The Judeo-Christian-Islamic notion of God is one that those questions should be addressed to.

Yet, this construct of God is limiting.  There are other interpretations of God.  Some bend towards the Polytheistic (Hindu, most notably) that explain the somewhat conflicting ideas of life by stating there are many Gods and they're a pretty dramatic bunch, always stirring up shit.  There's also the view I have, which is God is not the creator of the universe, God IS the universe.  Meaning that we are all smaller moving parts of a grander whole, which is labeled as God.  When you here some philosophers say "You have God inside you," this is the idea they're building towards.

I've made no secret that I'm a Zen Buddhist who leans pretty Soto-ish.  Compassion and empathy for a living things is a cornerstone of my beliefs, and it's rooted in this idea that we are all interconnected, all interdependent on each other, because we are all part of a grander whole.  As such we are simultaneously divine, and inconsequential.  These are not conflicting ideas.  If you've ever surfed, you've probably seen a wave that you'll never forget.  Giant, majestic, and wholly unique.  And after it crashes...it's gone forever.  There will never be another like it.  But...it's also just water.  Water part of the same sea that churns in on itself ad nauseum until the end of the earth.  It's unique, but not.  Special, but not.  Beautiful, yet ordinary.  Such is the way (in my opinion) with all of existence.

So when asking your question, know that there are three ideas of God (basically, they all can be reduced to three opnions).  One God, All God, No God.  Your notion of the divine manifests as one of those three.  For me, the "All God," approach engenders compassion, understanding, and patience.  Those are the virtues I value above all others.  Even when I get indignant about stuff (i.e. The People vs George Lucas, Twilight) it comes from a place of frustration, rooted in compassion.  Because I recognize there is no divine origin for the evil, malevolence, and selfishness that exists inside of me and every other living thing.  It's just a byproduct of living.  As sentient beings, however, we have a choice.  We can't choose to be rid of hate or indifference, but we can choose to not act that way more times than not.  When you reframe the questions that way, you may find yourself not needing to look to the sky to for an answer.

Is there a God? Probably not. Not the omnipotent being that most religions talk about, at least. But if your belief gets you through the day, then more power to you. As long as you aren't using religion to hurt people, I have absolutely zero problem with it.

Why would there be a god or gods at all? I'd argue that the notion of the divine, powerful being is an entirely human construct.

In recent years (like the last couple hundred years) a new concept has arisen of "god as the universe" (pantheism), but I've long felt that this was a somewhat arbitary way of describing things, since a nonpersonal and nonanthropomorphic god isn't really a being so much as an idea, and that calling it god was really some way of saying to theists 'hey, I'm not all bad'. Most are essentially atheists by another name.

Considering that the atoms in our bodies were formed in the core of stars, and that when we die, our atoms return to a part of the cosmos, the universe is our creator and our afterlife. I find that to be a beautiful thing, and spiritual I guess, but I wouldn't call it god in any traditional sense.

I agree that a definition of God must be offered before it can be meaningfully discussed. If someone wants to point to their toaster and call it God, well, their toaster clearly exists so I guess their definition of God exists, although I don't find the label "God" particularly useful as it doesn't give me any information about the thing that the label "toaster" did not.

This is the same view I have toward defining "God" as "the universe."

In a nutshell, I find conventional definitions of "God" to be improbable and without merit, and unconventional definitions to be nebulous and without value.

I think there is a need for a singular word that describes a persons understanding for the entirety of existence, and their relative place in it.  "Universe," is limiting, because it's a specific celestial territory, and as many people theorize, there may in fact be several Universes either sequential or simultaneous.  "God," is limiting in that it is generally a singular consciousness that created all or part of existence, but it says little about our place relative to existence.  I seek a word that describes all of everything, especially when I am trying to understand my place in all of everything.  God, in some ways makes a sense, as does Universe.  But I would agree that neither is fully sufficient.