Almost 450 MB consumed on empty external hard drive
My inclination is that your situation is both normal and expected.

I have a 500 GB UDB HDD with almost the same Bytes capacity as yours and the folders you list are generated on all HFS+ filesystems to allow several items to work. Additionally, my SSD that I have connected over USB also was recently wiped and had 71 files, 312.8 MB of space used on a totally unused partition and after erasing it, the files and space used went to 39 and 312.5 MB respectively:

Mac:~ me$ cd /Volumes/SSD 
Mac:SSD me$ sudo du -sm .Spotlight-V100/ .Trashes/ .fseventsd/
1   .Spotlight-V100/
0   .Trashes/
1   .fseventsd/


You should expect your .Trashes folder to be empty and little actual space used for the other two folders. They hold filesystem metadata and databases used for Spotlight as well as Time Machine and other tools that track filesystem events. As you can see, I have 2 MB or so of allocation but 312.4 MB of space is not usable due to block allocation sizes, filesystem reserved space and other overhead.



You can use sudo ls -laR to get a complete listing of all the files on your disk. Also, the OS will recreate these files if you ever delete them, so your choice is to use HFS+ and let these exist / grow as needed or choose a filesystem that doesn't pre-allocate this space on that drive.