Help with PUrchase, Ultra Wide Lens & Body for Real Estate Business (Indoor Shooting)

Hello everyone.

I am fairly new to photography and have a few questions and would appreciate any feedback from the experts. My question is split into 2 parts:

We are in real estate business so we need a high end ultra wide lens and new camera body. In the past, I used a Canon Rebel with 6 megapixels, however, was disappointed with light and color contrast.

Question #1

We are looking now to upgrade and were suggested the following items:

Body: Canon EOS 550D
Lens: Canon EF-S 10-22 f/3.5-4.5 USM
Both of these appear to have very good reviews and it seems both these items would result in around $1500 or so in total charges.

With a budget of about $1500-$2000 for both lens and body, would the above options be ideal for us? Our shots are almost all indoors and often with not too much light.

Question #2

For another office location for the same business, we also need a camera with wide lens for real estate. However, for this office I am looking at possibly going with Sony and the following lens:

Sigma 10-20mm f3.5

I am not yet clear on which body to get for this lens. For office #2, we intend for the camera to be higher end than Canon so I was thinking Sony was it. If we have a $2000-$3000 total budget here, what are our best options? Again, the goal here is indoor real estate shoots, with minimal adjustment on PC of images.

Any help will be greatly appreciated.