Oh boy, time to start another hate thread!
First things first, you've used the d50, did you not like it? Why was it so limiting, have you read the manuals and learned what everything the camera can do? (not saying its an intricate camera, but have you taken the time to learn all the smaller feautures or just the basic ones.
Secondly, why are you considering spending $2200 on a camera you've never used, with a brand you've never used (assumed) and using glass you've never tested? I don't know a whole lot about Canon but I feel as if the 40d may be excessive in your needs. ( For a few reasons in which I will politely as possibly state: You asked if those lenses had AF, You've never had a camera before, just used your dads, In your cameras you were previously looking at you included a Sigma Camera.. who here even knew they made cameras? I sure as hell didnt.)
My suggestions, would for you to scratch the 40d, and to look into the Rebel Line. It will be cheaper (as you wished) and will be plenty enough of a camera for you. I think that the Rebel XSi/XTi is what people enjoyed and found sufficient enough, I think some were troubled with the T1i?
As far as glass, I would also recommend the Tamron 17-50. I have the lens and have no issues with it at all, the AF seems slow at times, but I usually blame that on a new battery as switching them out usually makes the AF more responsive. I might also back the 50mm 1.8 as I have Nikons version of the lens. Im not sure on the tubes though, as I have never used them. I almost wouldn't buy a 70-200 now. Once you figure out the camera in its entirety, and feel limited by a 50mm then look into the option. But I can honestly say a 70-200 is my least used lens. They feel too limiting to me, but Im a sucker for wideeee.
Hope that helps, and consider this.. are those macro shots worth the $2000+ price tag?