Hello:
#1 My understanding is that the Feature Service will need to be hosted online, either through ArcGIS Online or through ArcGIS Server.
#2 I cannot explain the Location Tracking service.
#3 To create a basic service that you can update, I believe you should able to do something as simple as "Add item" in "My Content". The item you're adding could be as simple as a CSV with defined headers. When uploading the CSV you'd need to make sure the "Create a Feature Service" box is checked in the upload form/popup. After that you'd just need to make the Feature Service "Editable" by visiting the Feature Service that was created, clicking "Edit" and then checking the desired edit option (e.g., add/edit/delete, update only, add only).
#4 The email update would be a custom feature that would need to be developed, possible via a custom ArcGIS iOS application .. at least to the best of my knowledge.
Hope that helps a little.