You shouldn't have to worry about the voltages for the PSU. The majority of computer components nowadays run off the +12V rail of the PSU and there's plenty of juice available on the +12V rail of that Corsair model to handle what you need
Lol nah it's really not that bad! Fitting the new one to the case is only a simple matter of four screws and then you just need to plug everything in. It's up to you how much time you take to get it all tidy etc but obviously the tidier the better really for airflow as well as for aesthetics! When you start drilling your own holes for cable management is when the fun starts Good luck!
Back in the early days of personal computing (ancient history) static electricity was considered an issue. I remember having an anti-static wrist band with a long green wire that I attached to the ground wire of an electrical wall outlet (mains). I also had a very large anti-static mat under my keyboard. It also had a long green wire that was attached the the ground wire of an electrical outlet.
In modern times it is no longer considered to be a major issue.