I'd personally recommend getting the i1 Display Pro colorimeter for use with this monitor. I've tested both it and the Spyder 5 on my BenQ SW320 and various other monitors, and both copies of the colorimeters I own produce acceptable results. But years of experience and testing numerous copies of different models of X-Rite and Datacolor devices have convinced me to trust the X-Rite devices more. So that's what I use myself, and recommend.
I don't use the ambient light adaptation function of any of these tools. I feel it's a bit of a gimmick that solves a problem the wrong way. IMO it's far better to work in a work room with stable ambient light, or to control the ambient light in your work room if it's highly variable. Also, using the ambient light adaptation of any of the calibration tool's own software packages (X-Rite i1Profiler or the Datacolor Spyder software) would by-pass native hardware calibration of the monitor, which defeats part of the benefit of having such a monitor. The solution for me is controlling the ambient light and using monitor hardware calibration.
You don't need to set any colour options in the operating system. Palette Master Element software, or the colorimeter's own native software, will automatically set up everything that needs to be set in Windows 7. Windows itself has very little in the way of colour settings; mainly it's just installing the generated ICC profile and associating it as the default profile for your monitor. Beyond that, everything to do with colour settings typically happens within applications. Depending on what software you're using, you may or may not need to manually configure some things within app-specific colour settings.
I believe X-Rite and Datacolor calibration software typically can be installed and used on multiple computers in accordance with the license terms, but your best bet on that is to consult the actual license agreement on the package you're considering buying. I'd look it up on mine but I never keep that documentation.
Having gone through that, you say you don't need "extremely accurate color matching", so some of how I've described going about it may be moot for your case. Perhaps you don't need a hardware calibrated monitor. Perhaps you don't even need to calibrate at all, and could simply use one of the monitor's builtin presets like its Adobe RGB mode. If you share some info about what you're trying to accomplish and what your tolerances are, perhaps we can offer more useful input...