Quote Originally Posted by tycopolis
1. Can I just copy my data to the External drive without doing any partitioning or formatting? Once my Ubuntu is back up and running, will I be able to just simply copy them back?
You should be able to copy files to the FAT partition just fine. Make sure that you mount it as read/write, not the default read-only. I would caution against using the NTFS partition. If you need more space than the FAT partition provides and you don't need what's currently on the NTFS partition, considering repartitioning it and formating it as FAT also.

Quote Originally Posted by tycopolis
2. How can I delete everything on this External drive, and use it like a regular "thumb / flash" drive?
This is just a partitioning and formatting question. Use whatever partitioning tool that you are comfortable with (for me that's Ranish but I think I'm in a manority there). Figure out how you want the drive partitioned, make the partitions, format them (some tools like Ranish do this in the partition operation, other like Microsoft require a seperate format step). I would suggest saving this for later, recover your data first.