Everything you say is true, and there are no guarantees. Most (not all) patches can be uninstalled if you have problems. Having said that, after it has been out in the public domain for a while - you should consider that patch safe. It is better to have your system maintained and up to date (unless you don't use your computer on the Internet at all). Finally, if your software is legal there is no cause for concern. When you perform online updates, your computer doesn't send that type of information you listed anyway (only system information).
Having said that, EVERYTHING you do is traceable to a certain extent. There are registry settings, hidden folders, and hidden logs on your computer. Every data packet you send contains hidden hexidecimal identifiers (even when posting on this forum) - kinda like the VIN on your car. If you use that car to commit a crime, it will be easier to trace and identify the owner (one of the reasons that caught the kid that developed the varient form of "blaster").