Masters in computer science, any specialization like software engineering, database or even networking.

Mostly people do GC in EB2 only and those who do in EB3 keep looking for job that does EB2, or those EB3 guys are quite laid back and relaxed that they can wait for 6 years.

EB2 - GC is not for your current position of the position they are looking for, it is for future position. your current position and salary even might not be that much required for the position the EB2 is asking for, but since it is a future position it does not matter.

Many good employers do EB2, good desi consultancies also do EB2. You need to find an employer that does EB2. You could ask the employer if they do EB2.

Generally for Eb2, they put an advertisement of a job position that need masters degree or high skills ( bachelors +  5 yrs ex ), then they collect resume and interview US citizens and everyone, when they cannot find any suitable candidate for the job, they will take their own employee and file labor certification that this employee meets the criteria for this position while they could not find anyone ( US citizens ) to fulfil that positioin, hence a foreign national has to be employed and has to be apply for permanent residency based on employment. Once labor is filed , the process will start, I140, I485 etc.
This is general path. Some people actually go through this process strictly while some do above process just for sake of it so that their employee can get GC. That's how people get GC in EB2