Given you main needs are for indoor portraiture in natural light, fast primes are the way to go. You are looking at crop cameras, so in my opinion you will get the most benefit from lenses in the 28-35mm range, and 50mm. The 85mm lens is an excellent choice but unless you have a fair amount of room to back up, you may find it is too long for indoor use.
Faster lenses are best, so I would suggest Sigma 30mm f/1.4 ; Canon or sigma ( not released yet) 50mm f/1.4 - of these two, the Sigma promises HSM and better build quality - to start with. the 85mm is a lens that I want, but have left for the time being, having opted for a 100mm macro for now. the 85 can wait.
For outdoor portraiture, I prefer my 70-200 f/4 which is a stunning lens, the f/4 isn't an issue outdoors, and indoors with a properly bounced and diffused flash the results are excellent too.
I would also suggest getting a decent walk-about zoom lens, primes are somewhat limiting for many people's tastes for general use. The new 18-55 EF-S IS lens is an excellent starter lens, having image stabilisation at an excellent price, and having improved optics over its predecessors.
If you have more cash to spend, the 17-55 f/2.8 IS lens is probably the best walk about lens for a crop camera.
Regarding a body, unles there is a major saving to be made, go for the XSi / 450D - it is a significant step up on the XTi, especially if you take a bundled offer that includes the 18-55 IS kit lens.