GNU/Linux uses ext3 by default but can read a very wide range of them, including all the FAT versions.
Most external usb HDDs will work out of the box with YDL. Unless they have some sort of fancy windows-only features.
I use an old laptop drive in a usb enclosure. The enclosures special functions don't work, but it works as a UMS device happily.
You are asking very basic questions ... have you seen the documentation?
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