Ignore the 8MB...
If you want the partition to be a FAT32 you will have to set the size of the partiton to 32GB.
This is the limit for FAT32.
If you set it to 32000MB it will give you option to format in FAT32.
You will not create a dual boot.
p.s. Start again and delete all paritons the 8MB should disappear but when you create a partition it will come back.