In clarification, the commission that prompted my post is photographing short-term lets. Insofar as I'm aware, the images will just be used online to promote the lettings. However, the client has specified that they want images at least 4200 pixels wide. Also no fisheye lenses, flash only if necessary and preferably no HDR.
To be honest, from my experience this would make me a bit nervous. When I discuss RE photography with new clients I send them my portfolio, recent properties I have photographed, and often agents I currently work with. The agent's job is to sell the house and my job is to portray that property in the best possible way. There is no discussion of HDR vs. flash. I do not tell them how to sell the house and they do not tell me how to photograph. Often agents will tell me that they want particular angles or shots, but in terms of post processing + lighting they will receive similar shots to those I sent them. With agents I have worked with for some time there often isn't even a discussion on angles - they know I know which angles they want.
Personally, I use exposure blending in all of my RE shots. I tried going the multiple lights approached and found it took forever to get the lights in the right positions. I found that by using exposure blending the shots come out brighter and look nicer. There isn't really a right vs. wrong of exposure blending vs. multiple lights, but both I and most of the agents I know prefer blended shots.
In terms of time to shoot a property, it takes me about 45 minutes to shoot your average 1-2 bedroom condo and about an hour to shoot a normal sized house. Very large properties may take up to three hours over multiple visits.
In terms of post processing the average property takes about an hour. I use batch processing in Photomatix, do some color correction in Lightroom, replace the windows in Photoshop, then use the Nik suite + Photoshop to do some final changes.
If you are just starting out plan for about an hour and a half photographing the property and 2-3 hours of post processing. As you photograph more properties you will become much quicker. Plan for more time at the property if you are using lights as you'll have to experiment a bit to get them right.