Tom- good practice for a full bleed is to remove as much fluid as possible first, then fill to or near the top w/fresh. Then do the bleed in the order you state. If it has been a while since you last changed brake fluid, it should be obvious when the bleed is done. If you have fairly fresh fluid now, you wouldn't notice much color change, & you'll have to wing it. 2.5-3 quarts should do it. I've heard 4, but I think they were doing anti-freeze shots & beers at the same time.
Also good practice to do the pin-slide lube at same time IMO.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project