Two concerns about porting a project from windows to ios (or other platforms for that matter)

Hey there,

I recently posted over on the unity general support forum and didn't really get much of a response so I guess I'll ask over here in the iOS section.

I have a project that I've been working on for a quite a while that uses a simple single xml file as a central database for it's data. It simply loads the main database xml file on startup, then if a game is saved saves a copy of the main database that's been modified, or upon loading....loads the save game files which are just copies of the main database.

This is my first problem with porting. I'm wondering what kinds of problems I might run into with using xml.

The next is about flexible width and height. Right now I'm using a strictly set 1280x720 screen size. My thought is that the HUD would just be stretched from there and always stay at a 16:9 aspect ratio. I'm wondering if this is a bad way to go about creating a game if I'd like to port in the future?

I'm not only looking to get information on what problems I might find with iOS, but also with other popular trending platforms right now such as PSN.

Thanks in advance for any help you can provide!