You are not necessarily out of luck, but you are at the mercy of Ford's strict tiering system.Every Ford dealer that enrolled in the Dark Horse SC program and paid the entry fee is guaranteed at least one base allocation. However, Ford determines the exact level—Base, Track Pack, or Track Pack...
Both the Holley Ultra Lo-Ram and the Ford Performance Cobra Jet manifolds are designed for high-RPM power, which means they trade off some low-end performance for massive top-end gains.
Yes, you need to be concerned because precise fluid level is critical for the 10R80 transmission in your Mustang. Being off by even half a liter can cause major issues.
Yes, there is no specific all-in-one plug-and-play T-harness kit for the rear deck speakers, so you will need to manually splice or use Posi-Tap connectors.
Lowering your Mach 1 with the Handling Package will absolutely make street driving much more challenging. If you are already scraping at stock height, dropping the car will make your splitter problems significantly worse.