Not sure what approach you're stumbling with re: images, but they definitely support them, but you can literally just drop an image onto the editor and it'll embed it, including locating it where you've specified that attachments should go.
The default file per folder is not built-in, but there is a handy community plugin[1] which does it.
Right. That's the problem, it insists on storing images in a single folder, which doesn't scale or make it easy to manage complex notes as a single unit (it's the reason why my notes are folders and not single files).
No, you can put them anywhere, it just defaults to putting them in a single folder for ease of convenience. There's even a setting, "Default location for new attachments," which allows you to choose:
- Vault folder
- A specified folder in your vault
- In the same folder as the current file
- In subfolder under the current folder
But again, that's just the default location; you can put it anywhere and reference it wherever it is using relative paths.
The default file per folder is not built-in, but there is a handy community plugin[1] which does it.
[1]: https://github.com/xpgo/obsidian-folder-note-plugin