By holding down a fret with your left hand, placing a right hand finger on the string twelve frets higher (without pushing down), and plucking with the right hand.
Artificial harmonics, tapping,and arpeggios are good to learn.
There are no best harmonics.
Guitar. Tuning forks are a sine wave
A rythym guitar is an electric or accoustic guitar playing chords to keep rythym and the bass guitar is used to anchor down the harmonics and lay down the beat, basically smooth things out and either playing basic rythyms or beautiful harmonics.
Natural harmonics are produced on a guitar by lightly putting your finger on the 12th, 7th, or 5th frets. There are other ones but these are the most common and easiest to use. IF you want to know more about them and how they work there is a great vid on them at http://www.youtube.com/watch?v=5j2AxGGmT-g
Van Halen was very famous for tapping. The intro to Hot for Teacher and many parts of Eruption feature this. He also uses artificial harmonics along with very fast finger speed.
Those are called pinch harmonics.
A guitar is a far more complex structure than a tuning fork, and has more harmonics. The whole design of a tuning fork is intended to give as simple and pure a sound as possible, since that is the easiest type of sound to use when you are trying to tune an instrument. You wouldn't want harmonics in a tuning fork.
pinch harmonics are a guitar technique used to get really high pitched sounds by holding the pick with about 3mm of your thumb below it and strumming. If you do it right the string will bounce off you thumb after you strum and create a harmonic. This is incredibly hard to master and is affected by where you strum. This means that for every fret there are certain spots on the string you can use to create pinch harmonics that you can either find by trial and error or if you know how harmonics actually work you can find them fairly easily. There are a lot of youtube videos explaining this and how to find the harmonic locations but this is incredibly hard to learn and even harder to get them to work with any regularity.
This depends on what type of guitar you are using. If you are using an acoustic guitar then reshaping will harm the sound. If you are using an electric guitar it will not, but you must have the strings set to the same tension after you have reshaped it.
artificial
if the neck fits in the joint absolutely , but make sure to intonate the guitar so the harmonics line up with the neck which is something big for experienced players, very easy to do. Tune the guitar perfectly than do harmonics on the 12th fret and adjust the bridge until they're dead on. It sounds hard but it isn't. also make sure the neck us sitting on the guitar right because this could create problems on the neck with playabillity. I modified the neck on my main guitar and it didn't sit right on the neck at first and i had some dead notes which went away when the neck was perfectly straight. but hope I could help.