Homebrew,
You noticed that Volvo does a nice job of protecting the optional fog light connectors from corrosion or damage; they don't just leave them hanging there. A clear advantage of the factory lamp assemblies is that the mounting points already exist, so installation is straightforward (though the top screws may be a challenge unless you have a flexible Torx driver). The factory lamp assemblies also include vertical and horizontal beam adjustment screws. If you decide to use aftermarket lamps, you will have to design and make some sort of adapter or bracket (I did this on my S70; not that hard), and cut off the factory connectors.

My comment about the factory fog lamps being primarily for appearance reflects my personal opinion, not Volvo's intent. I like to use fog lamps not only in the fog, but on country roads to light the edge where roaming deer and racoons suddenly jump into your path. The factory fog lights are fine as an aid to oncoming drivers seeing you, but do not meet my expectations overall. Does this mean they are inferior? No, it just means that my personal needs differ from what Volvo intended to accomplish. City and Autobahn drivers have different priorities. The reason we have such a huge after-purchase market for non-replacement parts is that many drivers like to personalize their vehicle to match their preferences. Volvo designed the S80/V70 features as a compromise to attract buyers in all of the entire world's markets; they cannot be faulted for not satisfying everyone. The choice of OEM or aftermarket lamps is your decision. If you prefer to avoid the hassle of customized mounting, then the factory lamps are probably the way to go.

As far as needing a software download to activate the function, in the future this will be common to most cars. 25 years ago, who would have thought most cars today would require a separate computer to operate the engine, transmission, and brakes? As the use of the technology matures, you will be able to download the software over the internet yourself, or perhaps at the "cyber counter" at your local Pep Boys store. For now, it's Volvo-proprietary.

For many years, Volvo has not made a comprehensive shop manual available to individual buyers. I can only speculate on the reasons. They operate a web site (www.volvotechinfo.com) where you can purchase wiring diagrams and service bulletins. They are expensive. Eventually, once their are several hundred thousand of a model in service, the market size will stimulate Chilton's or Haynes to publish a manual. For this very reason, I would never own a Volvo that is out of warrantee. Unless Volvo perceives their policy is limiting new car sales (I do not think it is today), they have no incentive to change it.

There are several dealers in the USA that sell factory parts (such as filters, brake pads, and spark plugs) by mail order at a discount. Volvoparts.com and Borton Volvo are two that I am aware of. I purchased replacement cabin filters and brake pads from Borton.

Send me a message at n0v8or@cox.net, and I will reply with images attached.