There's a fan header specifically designed for the CPU, and there's a fan header designed for the case fans. If you have one CPU fan and two case fans, plug the CPU fan into the CPU_FAN header (near the CPU) and buy a two-way fan splitter for the case fans. If you already plugged in the CPU fan and there are 3 case fans, buy a 3-way fan splitter and plug them into SYS_FAN1.
2-way fan splitter: https://www.amazon.com/Rosewill-Spl...+fan+splitter&qid=1567367760&s=gateway&sr=8-7
3-way fan splitter: https://www.amazon.com/Phobya-3-Way...+fan+splitter&qid=1567367787&s=gateway&sr=8-4
As long as the bios is set for the headers to be controlled auto/voltage and not pwm, then yes.
That's a pwm cable but yes it'll work just fine, the 4pin cable has a tach, the 3pin cables don't. So 2 of the fans will be running at what ever voltage the header sets according to the third.
I do have one question, since these are 3pin analog DC voltage controlled fans. Exactly what does the fan say on the back, in either A or W. Your fan header is only rated at 1A, that's 12W. If all 3 fans add up to more than that, you can only use 2 or you'll fry the header.