display multiple PDF files on screen

we need an application that can display on screen N PDF files in a row that will be found in a local directory. The display order is given by file timestamps, where the oldest files are displayed first. The file containt of the directory can change at any time, so the application cannot lock the files (a different application must be able to delete / update / insert PDF files at any time). The file scroll speed must be set by the user. All the relevant settings (i.e. the directory path, the scrolling speed etc) must be read from an INI file. When the application is run, it will scan the given directory for the file containt. If no PDF file is found in the directory, a standard PDF file will be shown with a user defined message (sort of 'no news to show'). The standard PDF file will be found in the application directory. Every N seconds (this setting must be set by the user, too) the application will search the file directory for a file list update. According to system time and week day, some files will be judged old and deleted. If some change is detected, at the end of the current file, the new file list will be started. Whatever the application action, no effect at all should be visible in the scrolling process: the scrolling should be 'smooth' at any time. The application must be written in Delphi (v. 5 or v. 7). Theoretically the application when started should run forever, so the utmost care is required again memory leaks. The coder will have to report the tests he run with some kind of memory leaks fix tool. The application will work with any kind of PDF files: some files will be short enough to fill 1 page only. Others will extend over multiple pages. The user should see a smooth screen scrolling at any time, any way. Care must be taken for special cases, like 1 PDF file only, as short as to fill a half screen page only. In this case, no scrolling is done. All PDF files will all have the same horizontal width, so the zoom scale will be fixed (another setting in the INI file).