Q: Beeps, squeals, and whistle sounds in brakes

"It’s about a 1 mile round trip on my lunch break to home and back. While running in to grab my lunch, I left the SUV running. After getting into my vehicle, I pressed the brakes and heard a continual, long beep. It didn’t stop until I shifted back from drive and then into park again. I assumed it was just a glitch, so drove back to work. Three hours later, I’m driving home and stopped to fill up my tank. I got out of the car and as I did, I pressed the brake pedal (semi-way down) and there was that beep, but it had become a loud squeal instead and seemed to be coming from the brake system. --For the past ½ year, there has been a fluctuating whistle sound from the engine 24/7 (driving, idle, always in Reverse or Drive but a lower volume in Neutral). It sounded like an air leak, but nothing was escaping, it just sounded that way. The dealer told me that was normal. --In the mornings, the brakes always slightly squeaked when first driving. Plus they pulsated like going over tiny bumps when coming to a stop. Again, the dealer said that’s normal. --Back to the gas station… I pressed the pedal to try to replicate the sound and then I realized it was the brakes and they had a spongy feel to them, then they became hard -- just very different than they should be. I’ve never felt them like that before. Then the whistle started again. Then quit. The pads seem very hot. There’s no hard braking. What happened to change the brake sound and it’s consistency and what should I do?"