First off, welcome back. What kept you?
Secondly, congrats on the new car. Looks like a winner.
I would start by finding a mod-friendly dealer to work with. Check the regional forums for guidance on this. There are plenty of dealerships that don't hassle customers about modifications so putting up with a dickhead service writer is not worth it. Nor is it worth removing aftermarket parts every time you go in for service. That said, buyer beware on upping the boost. A piggyback tune will cause the ECU to store shadow codes that can be seen by the dealer if push comes to shove. Many people will tell you that the dealer has no way of knowing you have a tune if you remove it, flash it back to stock or whatever but this is simply untrue. There are not a lot of issues of BMW denying claims but be informed when making decisions. As for the smog check, you will still pass so long as you get what is commonly referred to as a "DP fix", or a small device to shut down the cat efficiency code and warning light. No lights in the dash, no emissions codes from the ECU, no issues passing smog. Remember, you have a secondary cat downstream that is sufficient to pass.
Enjoy the car...