Create a Video Greeting Card based on user inputs

Hi, I'm currently working with a developer to create my website - it's a video greeting card service. My developer is working based on 'designs' that I've given him but we need a designer to help bring this 'over the top' and make the video greeting flow beautifully and seamlessly. The video card is based on a series of images, text and finally a personal video that the user uploads to the website themselves. All will be done to music based on the occasion or theme selected. Since the user 'designs' the card based on inputs (occasion, card design, text message), this video would be a collage of these inputs to create a final output. I also have an idea of how I'd like it to be so in my opinion, it's pretty simple and clean. Based on the above, could you let me know what else you need from me to provide an estimate of time and cost?