Image Design Interface

I am after an interface (preferably to be used in a worpress blog style page) that allows people to change the text of an existing design by typing into a text field and having their word come up on the screen (created by a series of jpg letter images that display next to each other). For example, the character 'a' is typed in the text field, which accesses a database of alphabet image files, pulls the relevant image out and displays it on the screen. I am currently working on an alphabet set of image files of both Upper and Lower Case. I want to have the option for users to save the final image as large as possible. The current image set I am creating are small in file size so shouldn't be too much lag time in loading the images. I understand that general font characters are different widths (eg an 'i' is much narrower than a 'W' - so consideration will have to be made in terms of how these jpg images will appear on the screen side by side. Important Requirements: - To be able to embed into a wordpress blog (with possibilities of having this interface appear in a larger window/lightbox. - Nice clean interface (potentially with the option for me to customize in the future) - Due to the range of word sizes and lengths, the final output on the screen of these images will need the option to be scalable to fit centred on the screen. - The option to have a watermark image over the top of design that can be removed. - The option to add different backgrounds (Load your own) - For the database to be easily added to and robust for potentially many users accessing files at once. (Linux would be preferred but my knowledge of this is limited so will need to discuss further.) - For this application to be duplicated easily and adjusted to fit other design dimensions, background images etc. (For example - Design_0001 May have a 3000 X 2000px final save option with a textured background. But Design_0002 may be 1000px X 1000px and have a flat colour that could have a colour wheel option to choose your own colour. - Clear documentation explaining how to implement in to my existing website, how to add a new design set of letters and how I can duplicate this interface and have it display the relevant design for the particular blog post. - (Skype access would prob be a good way to clarify certain points) Secondary Additions (May have to be considered in version 2 down the track) - Option to save completed design. - Options to add text over the top of design (accessing various fonts) - Options for people to login to access previous saved work (a bit like vistaprint) - Option to pay for image designs once complete and access a pay cart option where watermark is removed and design can be saved in full resolution.