Hi Martin!
Good questions!
Yes, the users can set pictures of their cars as background. In fact that was the original idea, their car pictures will play as a sideshow in the background (hopefully that won't be too distracting )
So far we are absolutely focused on making the best experience possible for the users. So we are still in discussion of the charging plan. We will probably have free accounts for up to three car profiles, and a small charge on pro accounts.
The information will be stored online, user can download them (i.e. pdf, spreadsheet) if they choose. This feature will appear on a later version.
Regarding security, we are still working on it so I don't really have an specific answer for you now. In terms of security, other than personal information, do you consider the car parts information a security threat? (Not the location, license plate etc, but the parts details)
Hopefully that answers your questions. I send you an email with my contact info, feel free to contact me.
**Side note: The miata is actually own by Ken from Garagestar.com. It's one of the best miatas in the region....feel free to drop by if you are in North California and mention SPEC!