• No. Aperture runs on OS X only. You can export to various formats, but then you and your client will be using other software, which seems to be outside the use you are asking about. Furthermore, Aperture is a single-user application.
•• No. Aperture is a self-contained image database. You can round-trip images to external editors, but doing so creates new files. This is useful when Aperture is your primary image repository. It does apply to your situation. Aperture should be thought of a photographers tool for managing a photo workflow from camera to published photograph. It is not a graphics platform for creating or storing graphics files.
••• No, there is not.