I've still got the 450D, but hardly use the 70-300mm, so my advice would be to get a decent walkaround lens with a body, don't buy a body with a kit lens, it's gonna end up in your camera bag forever once you get a decent walkabout. Then after several months, check your images, are you going long or wide, landscape, sports, portrait, etc - once you figure out what you take photos of, use the remaining money you have to service your lens and filter needs.
I agree with most everything you said... a couple things to think about is lenses, on average, especially really good ones, will stay in your bag for many many years (and camera bodies for that matter)... You can get a kit lens and "learn" but they tend not to keep their value once your ready to upgrade and it (especailly once you move on and can compare better), aren't as good of lenses.
Personally I like the xxD series over the rebels because of the LCD's, ergonomics, size, etc etc however it is a personal matter and perhaps thats where you should go to a camera store and hold the different bodies, do your research and find out the differences and weight the price differences to see if for an extra $100-200 a top LCD, stronger body, ergonomics, etc...is worth it for you or not. To some it will, to some it will be seen as a simple "splurge"... Only you can answer that. Lastly bodies get replaced every 12-18 months (for consumer grade bodies) and lenses on average can go much much longer before upgrades, sometimes decades, see the 17-40mm L. If you had the option in your budget, spend more money on lenses than bodies.