I would print a selection of your actual emails, not just the headings. They will want to get a sense of your relationship, how the 2 of you relate to each other and what your conversations are. Subject headings will not tell them that. My husband and I wrote to each other almost everyday for a year and I printed every one (well, except a few!) If something is very personal, you can cross it out with a black marker. If I were you, I would print about 200 of your emails and then state that this is just a selection and that you have more available, if they need to see additional ones.
115 photos is probably more than you need but as I recall, you mentioned a large age difference with your spouse, so providing more evidence is probably not a bad thing. Make sure to have a selection of photos with the 2 of you and other friends and family so that all your photos are not just the two of you. Also, write on the back of each the date the photo was taken (doesn't have to be the exact date -- month and year is fine), who is in the photo, where it was taken and what the occasion was.
The letters from friends and family is a good idea.
Good luck!