1.) I am a department of 1 at a consulting firm and I handle all things related to infrastructure. That includes system administration, VMware administration, server administration, desktop support, networking, etc... On top of that I have been reading about and building computers for 20 years.
2.) Take your time and make sure everything is securely connected before you power on the system the first time. If you don't know where a cable goes, the front panel lights are always fun, consult the motherboard manual to help out.
2a.) Don't go cheap on your PSU. If your PSU dies it will most likely take a lot of other components with it, and cheap knock-off units are more likely to fail. That doesn't mean you need a $500 PSU for every computer, just means use known good quality manufacturers and if you don't know any do some research or ask on forums like this.