There's no a problem with the author's current code, since the padding is already included in the node size, but it would be a problem after doing alignment more intelligently.
Interesting. How is that comment homophobic? Might be factually incorrect, but not homophobic. Quite the contrary, it implies that women prefer looking at women too.
(Yes, you can store a filesystem in a file - and that's a trivial sort of disk image, but one with some serious drawbacks like "you have to allocate all of the space up front". We can do better.)
Some of the most popular disk image formats are basically a sparse file abstraction for non-sparse files and nothing more. You have a bunch of blocks, a table mapping each block to its virtual location, and a couple convenience headers.
If those count as a disk image when you put a filesystem inside, then I say a normal file is also a disk image when you put a filesystem inside.
Especially because the sparse mapping is optional. For example, lots of VHDs are a raw file plus a 512 byte footer.