Man..... I work at Best Buy! I used to run a Custom Shop and do a lot of magazine/show work, and you bashing retailers couldn't be further from the truth. The standards that a CC or BBY have to follow are far beyond what you'd find at most small shops, even repudable one's. Now not all CC's and BBy's are the same, meaning that you have some where the workmanship is amazing, others where they have a bunch of rookies. Before dismissing a store completely, maybe you should ask what backgrounds they have. You'll be surprised to find that there are a great deal of stores with very talented and experienced installers.
In regards to the grill coming off, haven't removed my rear deck, but I know that they can only be removed once the entire rear lid is off. Meaning that the entire interior behind the front seats must be pulled. I'll have a thread once I get to it, along with the HID kit, but you might want to try another forum until then. Also, when asking a question, it's poor form to complain about the answer just because you don't like/agree with it. If you're too good to take advice, save the time and bandwidth for someone who will actually use it for something productive.