Hope you enjoyed that, because things are about to go from depressing to despondent.
6. Why hasn't the United States fixed this yet?
Because it can't. There are no viable options. Sorry.
The military options are all bad. Shipping arms to rebels, even if it helps them topple Assad, would ultimately empower jihadists and worsen rebel in-fighting, probably leading to lots of chaos and possibly a second civil war (the United States made this mistake during Afghanistan's 1980s civil war, which helped the Taliban take power in the 1990s). Taking out Assad somehow would probably do the same, opening up a dangerous power vacuum. Launching air strikes or a "no fly zone" could suck us in, possibly for years, and probably wouldn't make much difference on the ground. An Iraq-style ground invasion would, in the very best outcome, accelerate the the killing, cost a lot of U.S. lives, wildly exacerbate anti-Americanism in a boon to jihadists and nationalist dictators alike, and would require the United States to impose order for years across a country full of people trying to kill each other. Nope.
The one political option, which the Obama administration has been pushing for, would be for the Assad regime and the rebels to strike a peace deal. But there's no indication that either side is interested in that, or that there's even a viable unified rebel movement with which to negotiate.
It's possible that there was a brief window for a Libya-style military intervention early on in the conflict. But we'll never really know.
7. So why would Obama bother with strikes that no one expects to actually solve anything?
OK, you're asking here about the Obama administration's not-so-subtle signals that it wants to launch some cruise missiles at Syria, maybe with the United Kingdom, which it says would be punishment for Assad's strongly suspected use of chemical weapons against civilians.