Aww, Raine *hugs* I'm sorry. That sucks. Hopefully he finds something good soon!
Some of the characters are vocaloids, some are utauloids; it depends on the company that makes them. But they're essentially the same thing beyond that - a singing program. (The very first vocaloids didn't even have characters, those were added to later creations to increase popularity.) Each one is voiced by a different person, who records sounds in various tones and pitches (it's easy to get all the different sounds used in Japanese words, since each letter has only one pronunciation; hence they sound much smoother in Japanese than in English.) People who buy the software can create their own songs or do covers using the provided voice and they're often uploaded to NicoNicoDouga (sort of like a Japanese youtube, I guess?). There are some really popular producers whose songs are frequently used for the concerts, though which songs are used probably just depends on their individual popularity.
My best friend adores Miku - "Obsessed? No. In denial? Maybe."
The holograms are awesome! I think holograms are really cool in general
