First, check out JD Application Process | The Law School Admission Council</a>
for the process/procedure of applying, specifically for GPA matters.
Second, based on a cursory review of the websites of the top schools, it appears that “soft” factors play a role in admissions. That said, the LSAT is a gigantic portion of your application, and will be determinative regarding not just admissions, but also scholarships/aid, etc.
Third, while it’s always good to plan, you’ve got a big variable(LSAT) hanging out there, so it’s a bit premature to focus on any specific area of law. Based on my experience, only the top students at the top schools are fortunate enough to select what type of law they will practice; most of the rest will need to entertain whatever offers they get.
Fourth, what is your financial situation? Law school is extremely expensive. At best it’s ambiguous as to whether a Master’s will help in admissions-but the first question to ask is if you can afford it. It’s worth calculating the projected cost of law school with and w/o a Master’s.