How good a camera can I get for $600?

I like the Canon G series. I use the latest one, the G16. It does everything you listed, except for maybe number 5. You can't shoot zoom in bad light and get good results without spending tons of money. A lot of camera nerds bag on it online, because it doesn't have a big sensor like the latest Sony, and they removed the articulated LCD, but I still use mine way more than my 7D.

Ok, I bought a Nikon D3000 and 3 lenses used from KEH ("bargain" grade) for $240 with shipping. Everything works perfectly, and there are only the tiniest cosmetic imperfections on the camera (like stuff that would happen anyway with a few weeks of normal use). I'm not going to impress any of my rich friends with my bargain-basement gear but the pictures are just as good.

I wouldn't recommend a DSLR for most people who aren't serious about photography. Don't get me wrong, I shoot a DSLR myself and I would never give it up. But the benefits of a DSLR only make sense if you're planning on investing in the hobby. For instance, a DSLR lets you change lenses. If you are going to buy/rent additional lenses, this can be a fun, inspiring, and totally worthwhile benefit over a point-and-shoot. But if you aren't actually going to try different lenses, this won't matter to you. Similarly, a DSLR packs a high-quality sensor and lets you shoot in Raw, which allows you leeway to push around the pixels in post-processing. But if you aren't going to learn Lightroom or Photoshop, then again, what's the point? You listed eight criteria. Of those, only #8 jumps out as maybe requiring a DSLR, and even that you can easily accomplish with a point-and-shoot that includes manual shooting. If you want to buy a DSLR, go for it. I love mine. But if you hadn't specifically mentioned a DSLR, I don't see anything in your question that would have pushed me to suggest one. As for learning about cameras, I'd suggest reading reviews. http://www.dpreview.com is a good starting point. They publish their own reviews, and you can browse their forums where people chat endlessly about gear. That's really the only way to learn about all the gear that's out there. Of course you've gotta use it to really understand it, but that's later.

The Wirecutter's Best Mirrorless camera under $500 is now http://www.amazon.com/exec/obidos/ASIN/B00BF9MUBM/metafilter-20/ref=nosim/. This is a steal. The Sony 55-210 lens (to get you your zoom) is another $350, so it is over your budget, but it's an excellent camera. There's also nothing wrong with superzoom point and shoots. There are certain things they don't do as well as SLRs, but they are more convenient and they'll produce good images for the money. Buying a used/refurbished SLR is also an option, as others have mentioned. Good luck!

Paying full price for a camera is just not a smart thing to do unless you are an established pro. Fortunately, new and second hand deals are abundant. Given your questions, Old Man McKay is pointing to a very good recommendation. Once you get to know the camera, you can put the rest into one or more lenses that better fit some of your specific needs: fast primes, wide angle, long zooms, etc.

I am thinking about getting a Nikon D3000 used for around $200 with kit lens, and then getting several used 35mm lenses (probably just MF to save money). I don't know if this is a terrible idea because I haven't done it yet though.

In addition to the Wiercutter, the https://www.flickr.com/cameras might be helpful.

a deal like http://slickdeals.net/permadeal/112792/ebay---nikon-d3200-24.2mp-digital-slr-camera-w-18-55mm-vr-dx-af-s-lens-refurbished on a decent DSLR, plus a 35mm 1.8 lens and a 55-200. this will completely be possible for $600 if you wait for deals on the lenses, and check sites like craigslist and keh.com Note that this isn't going to get you to the good low light performance WITH zoom, but to get that you'd need to buy something like a 17-50/55 2.8 which will cost as much as the majority of your budget. It will get you good low light performance without zoom though, and everything else you wanted.

An entry-level DSLR coupled with am 18-200mm lens should just about fit in your budget. It will not be great at low-light shots but will be ok, and likely better than your camera or point and shoot camera. You can add lenses as you go after that if you are getting enjoyment out of it. Just be aware that is f you do start buying more and better lenses you will likely get rid of your initial lens and camera.