Here are some thoughts..
1)Not totally clear on how many years you spent at each school but the actually cum GPA is not all schools look at it when it comes to academic record. They look at GPA, major, type of coursework, rigor of degree, quality of school to make their assessment of this part of your application. So this does involve looking at each transcript independently.
2)Your 4.0 definitely will not be accepted as your cum GPA because it is not if i understand your academic career properly. Theres no one set score you need to get for the GMAT but it is always safe to hit or exceed the average for obvious reasons. Generally the rule of thumb is the lower you are below the avg GPA the closer/higher you need to be in relation to the avg GMAT score. Keep in mind this is a very simplified way to look at this.
3)Your law school GPA is more proof of being able to handle graduate level work but it will not be combined with your undergrad GPA. Business and law are very different so its not a direct comparison but this is seen as power degree so if your career goals align with your decision to get a law degree I can see this being potentially helpful. A question they will have is why another grad degree? If your answer and rationale is not clear hear this could be a negative as you may be seen as someone who does not know what they want to do.
4)I would say there is a lot of value in utilizing an admissions consultant particularly someone like you who has a non-traditional background and needs to package your profile in the appropriate manner to be successful
Hope this helps!