Sure there are hex converters and editors for Linux, but Notepad++ is a text editor that handles binary as if it were just another text file. For example if you try in Vim to edit binary files beyond very simple edits, it'll usually corrupt them. And from `hd file.bin | less` you can't edit them.

For hexdump, I could never remember which switch gives me the format that I want to see. I'm now using xxd, which comes with vim and has nice defaults.