Another suggestion I would give you is when you are ready for your sealant....or wax...or both.....make sure you get some product that is meant for a dark colored car. I went with Menzerna's Full Molecular Jacket (sealant) which is made specifically for dark cars. I also have a black saph, and the FMJ is incredible. Makes my car look "wet" all the time. I like it so much that I no longer use wax. If you do happen to prefer a couple coats of wax, Poorboys Natty Blue is also specific for black (dark) cars.
BTW I know how you feel about being in kind of a whirlwind with all the products available. I credit this forum with a ton of great information that really helped me sort everything out.
07 335i sedan | Steptronic | Black saphire | Terra | ZPP | ZSP | Cold Weather | CA | PDC | Nav | OEM Alarm