1) I agree with Maintain - connections (and your persona) are going to be more important than anything else. Further, music and other arts degrees are not highly represented in the legal profession. This doesn't mean that people can't get work, it just means that, compared to other degrees like political science, those who have a BM or a BFA are not as likely to go into law. That said, from my network, the people that do
go into law with those degrees do rather well. Several use their arts degree as a vehicle to get into the entertainment industry (look up entertainment lawyers working in LA) or use law school as a vehicle to transition into a different industry (look up those degrees in mega big law firms in NY). I know of an attorney who has a BM and a JD, and President Obama recently nominated her to be a federal judge. Most of my friends from music school that decided to go into law have attended a top 30 school. I view it as a double edged sword. On the one hand, you will be viewed as a bit of an outcast because you have different background. On the other hand, you will be able to bring a unique perspective to collective, creative problem solving. In other words, the degree itself is not inherently bad. Whether it is positive or negative is going to really depend on you and the narrative you present to future employers/law schools. Heck, if Reagan (an actor-turned-politician) can become President - you can get into law school.
2) A lot of people (most people) don't end up practicing law. I agree with Maintain - in most situations, you should only go to law school if you actually want to practice law. Of course, there are exceptions. If your family has enough money to pay for it all and going to law school (and working) is more so something to keep you occupied as opposed to a necessity, and you have a deep desire to go to law school... well then, by all means. That said, tons of politicians have law degrees. The training you'll receive will be useful, but by no means necessary. If you are asking whether a law degree will hinder your chances at politics - I would say it would likely not. I mean, it will likely take to time to pay it off - and if you start a family and have kids to attend to, it might hold you back from fully pursing your interests.
4) Maintain answered it.
5) You shouldn't. You'll have interests between now and law school (music), but other than that, you should enter law school with an open mind. That said, if you do have a demonstrated expertise going into law school, you will have a leg up to your peers. Employers do like it if you can say: this is what I have done with my life, this is what I loved about it, this is why I am going to law school, and therefore I obviously want to do transactional work. On the other hand, if you don't have a demonstrated interest and you randomly say the only thing you want to do in life is working on M&A deals (i.e. you are not being sincere), employers will see through you. It would be far better in that situation just to say something like: you really enjoyed your contracts class, property class, and drafting contracts in legal writing, and think you would enjoy working in that, but that you are eager to see what other practice areas are like.
6) I'd say GPA and LSAT amount to about 2/3 or 3/4 of your chances in law school admissions. If you are an underrepresented minority, you will likely get a solid boost there. So your "soft factors" will likely only tip you (or not) over the edge. Generally, the more unique your background, the better (i.e. the more diversity of experience you bring). So an arts background (assuming you tie it into your narrative appropriately) would likely help you out a bit. But again, this is not going to overcome a lousy GPA or LSAT. This is why people say to do an undergrad degree that you enjoy as opposed to one that you merely think will "help you" get into law school. If you actually enjoy what it is you are studying, you are likely to do better in school. The better you do, the better you chances are at getting into a better law school.
7) Straight economics - no. But depending on the school you go to, you might talk about law and economics quite a bit. Usually, the more theory based the law school (which tend to be the higher ranked schools), the more you'll talk about this. The more practice based the law school (which tend to be the lower ranked schools), the less you will talk about this. But even then, law and economics is just a theoretical explanation for making policy decisions or anticipating a holding's practical implications on society. In other words, it is not the primary focus (or even secondary focus) of law school.
The LSAT tests two primary skills: reading comprehension and logical/critical thinking. The LSAT tests these skills in three forms: logic games, reading comprehension, and logical reasoning. Logic games present a factual scenario and ask you intricate questions about logical conclusions. Reading is a relatively non-factor in these sections. By contrast, reading comprehension sections present a few paragraphs worth of jargon filled, detailed, complicated text and ask you rather basic questions like what the main point is. Logic plays a real but minor role, it is highly subservient to being able to comprehend what the heck you just read. Finally, logical reasoning is somewhere in-between. It presents you with a paragraph of rather complex text and asks you intricate questions about logical implications that are based on your ability to discern nuances in the text. It tests logical reasoning and reading comprehension about equally. Note reading comprehension and logical/critical thinking is the basis for law school, but not the only thing. Doing well in law school tests your dedication to work hard and your ability to manage your time independently. Things that are sort of but not really tested on the LSAT.
9) I don't see why taking either the ACT or SAT at least four years before you take the LSAT would be of any help on the LSAT. As you saw in question 8, the LSAT is nothing like any standardized test you will have taken up to that point. There is no math, no verbal, nothing really substantive. It just measures your ability to read and reason. In other words, it is a performance as opposed to a knowledge based exam. You don't "study" for the LSAT, you practice. So taking the ACT over the SAT (both knowledge based exams) is a non-issue. Honestly, I wouldn't think about the LSAT or law school much between now and your junior/senior year of college. Right now, just focus on getting into a school and a major that you will enjoy. In undergrad, focus on getting the best grades you possibly can get while doing extracurricular that you genuinely enjoy. Expand your mind, become a cool individual, learn to love life, etc. That is what undergrad is for.