BMW 3 Series: Whistling Noise, Squeaky Brakes, and Hissing on Acceleration

It sounds like you have a few different issues going on. Let's start with the easiest one - the squeaky brakes. This could be due to worn brake pads or the brake disc surface is not smooth. I'd recommend checking these first. As for the whistling and hissing noises, these could be signs of a possible leak in your intake or exhaust system. Check for any visible cracks or holes in these systems. The hard start and blueish/white smoke could indicate a problem with your fuel system or engine. It might be a good idea to have a mechanic perform a compression test to rule out any serious engine issues. Please keep us updated on your progress and let us know if you have any other questions. Remember, if you're unsure or the issue seems safety-relevant, it's always best to have a professional mechanic check it out.