I'm trying to create a bootable USB for Ubuntu for installing Ubuntu on my Mac with Dual Boot. I have 2 questions. I am a complete noob. I'm sorry if these questions sound too basic or downright stupid.
First question is: when erasing my USB to filesystem format FAT32 (MS-DOS) and partition scheme GUID Partition Map (which can be done using Disk Utility GUI or on terminal with commands: diskutil eraseDisk FAT32 UBUNTU GPT disk4), and after erasing so, when viewing the disks using diskutil list, I see that the volume (for me, disk4s2) with name UBUNTU has Microsoft Basic Data as Type. But I saw on Wiki that Microsoft Basic Data is basically equivalent to MBR, which I don't want (I want GPT). Why is this, since I made sure to specify scheme to be GPT? Does it matter? For disk identifier disk4, the Type is Guid Partition scheme. How can the volume have a different scheme from its parent disk?
The second question is: if I am not interested in booting from USB but only interested in downloading the Ubuntu to my Mac, do I need a bootable Ubuntu USB? Can I not just have ISO file on it?