hmmmmm I once said 'I could teach a monkey to build a computer, but it takes a tech to figure out what went wrong' Its easy to build a computer, and half the time nothing goes wrong, 45% of the time its just a minor problem. That 5% is the part where you need to learn, adapt, and THINK. Thinking is something 90% of the population either don't know how to do, or are just to lazy to do. You'll probably be fine building it yourself, as you said you've had prior exp installing hardware, your thinking about building a pc, and your asking questions..... that basicly tells me you'll do fine. BTW wash your hands before you go handling stuff, oil on your fingers are not the best thing for components.
You don't need much in the lines of a toolkit, just a screw driver or two, anti static strap, everything else is optional.... pair of needle nose pliers come in handy at times, zipties can tidy up messy wiring, compressed air can(unless you have an aircompressor), and a massive assortment of screws you save from every computer build you've ever made, AS5 if you plan on installing a HSF, some 99% isopropyl alcohol or cleaning the old thermal paste off. and of course a dremel, a hacksaw, some glue, a sledge hammer, ohhhhhh and the manditory 18 pack of beer.