What area of law involves work with hardware/software technicalities of computers/internet?

And if you can at all, state an average salary or how it compares financially to other areas of law?

Two areas, which are primarily related. Intellectual property law, is a big area, and good lawyers get paid very very well. Do a web search on that and see what you find out a about fees.

The other area is patent law. They get paid well because they are also degreed engineers as well as lawyers. Consulting engineers start at $250/hour and so do lawyers. Since a patent attorney is both, double it.