2 Yes, It Completely Voids Your Warranty
All of Apple’s products are covered under a warranty. Apple’s Limited Warranty covers defects in Apple hardware and Apple-branded accessories for up to one year from the purchase date.
But if you decide to jailbreak your device, you compromise the warranty. Therefore, if anything happens to your Apple device, you will not be covered. You may have to buy a totally new iPhone if your device stops working. It may be possible to reverse the jailbreak before you turn in your device for repair, but Apple may have a way to find out if your device was ever jailbroken.