Optimum settings for Video watching on an Ipad

I am looking to figure out the best settings for converting a movie file into and MP4 and watching on an Ipad. I have narrowed my choice down to 3 programs Format Factory (my Favorite), Super and Handbrake. I have some 4.5 GB Vob files and some 700 MB AVI files to convert. I am looking to keep as a good a quality as I can after they are converted to MP4. Also would like to have Video stretch out to the entire screen when watching on the Ipad if possible. What should be the actual size of the file once it is converted. They are b/w 1.3 GB and 2.4 GB once they become MP4's and some of that may have to do with the length of the movie. I have attached 3 different Jpeg's of my settings when using Format factory. My Vob files have a frame height of 720 and a width of 480. My Avi Files have a Frame height of 256 and width of 640. Does the original size of the file effect what settings I choose for the converted files output. I hope this all makes sense and some people will share some of their ideas on this topic. Thanks