Welcome to AppImage, glad you like our distribution-independent approach.
I don’t think there is an “absolute” best way - the best hosting option depends on your requirements. I am mainly using GitHub Releases and Bintray, and I see pros and cons with each. Others like to host themselves, and also have good reasons for that.
If you are happy with it, then I’d say stay with it for Linux, too.
Both are equally suited. Any hosting is, really, as long as it properly supports HTTP Range Requests (which most servers do).
Conceptually no, although AppImageHub currently has some more knowledge about projects hosted on GitHub Releases (e.g., can extract the link to the author page, etc.).
Once we have published it, what would be the ideal instruction for users not familiar with AppImages?
You can link to (or copy and paste from) How to run an AppImage.
Apart from making the AppImage executable after download, should I recommend saving it to ~/bin as suggested by the Wiki or ~/Applications which is also watched by appimaged? In my opinion ~/Applications would be an easy-to-understand location for technically less advanced users. But Linux purists surely don’t like it as much as ~/bin.
AppImages are designed so that they can run from any location in the filesystem, although our optional appimaged daemon (due to technical restrictions) only monitors the locations listed at GitHub - AppImage/AppImageKit: Package desktop applications as AppImages that run on common Linux-based operating systems, such as RHEL, CentOS, openSUSE, SLED, Ubuntu, Fedora, debian and derivatives. Join #AppImage on irc.libera.chat.