I'm in the same position as yourself in that I ordered my car in 04 also. I have specced mine and I've been advised that it will be here first week Oct at worst. Regarding residuals, I can't say for sure, but I suspect that the residuals will be the same as for the E46 during the first couple of years while demand is high. At least thats what I'm hoping! I've had my E46 for 4.5 years now and have been offered £12,500 trade in from the supplying dealer, which is pretty poor even though the mileage is noew 88k. I'd still say "go for it" and enjoy!!
Cheers .. DC