The question thing is kind of like a stim. My son does it, too, but far less now than he did at 4. Basically, he's wanting assurance that all is right in the world. His world is full of chaos, and unpredictability, and his repetitive questions are just a comfort thing. Kinda like a warm security blanket. It's also a way of communicating that he knows how to do. My son still doesn't do a lot of back, and forth conversing. It's his way of connecting to another person in a predictable way that he understands. I will usually answer his questions, but every now, and then I do get a little over the edge with the constant talking, and I will tell him that "I'm all done answering questions right now. Why don't you go do x" I also know that at times if he is repeating the same questions over, and over in a matter of minutes that it means that he's getting overstimulated, and he's about to have a meltdown. He will do this a lot when we are socializing with others, and it serves as an emotional barometer that tells me when he's had enough.
The noises are stims, and there's not much you can do about them. It's his way of regulating his sensory system. Both of my boys do it. If one hums, and makes noises the other gets louder, then the first gets louder, and so on. Earplugs didn't cut it for that much noise, but I tried. If I feel like I can't take it anymore I just ask my oldest son (HFA) to please take his noises to his room, or be quieter. He will usually do it, after protesting a little.