I used to be highly skeptical of the value of Earvana nuts, so I finally bought a neck that has one. Is it worth it? Well, it depends on how much you value accurate tuning, and where you play the most. The difference is subtle, but definitely noticeable. However, it really only works on open chords. If you play a lot of open chords or melody/lead lines down in the first position, you'll love it. It seems like they just "ring together" better, and sound much richer. I even play with mega monster super-deluxe premium stainless steel railroad tie frets (6100s) which make it easy to sharp notes if you're not careful, and it's still almost magical.
Cost-wise, the Earvana is slightly
less expensive than my favorite solution, which is the LSR nut. An LSR install, if you have Warmoth cut it and you buy and install the nut, will run about $85. An Earvana install by Warmoth is about $70. A Graphtec installed by Warmoth is $30. No other option makes sense to me, although some people will have them cut for and install locking nuts. I don't know what that costs, but I wouldn't do it even for free. And of course, there's always the corian nut, but come on. Really? Spend several hundred dollars or more on a neck and install a straight corian nut?
As for doing it yourself, if you have to ask how and what tools you need, you don't wanna do it. Nut installations are critical.
Finally, you don't need a tilt-back head. Tilt-back headstocks and/or string trees are for poorly fashioned nuts and/or truss rod exposure, and in fact some nut installations such as the LSR and Earvana aren't possible (at least from Warmoth) if you have one.