I wanted to make this post to help people trying to get this achievement. I found there wasn't a lot of information out there and what was out there was out of date. 

If you have more accurate or additional information, please post below and i'll try to update the post.

Things i know contributed to the "Yearbook Editor" achievement: 

• Unlock all heroes (Some hero unlocks didn't contribute(?), pretty sure you don't need any DLC characters to unlock the achievement).
• Unlock all ships.
• Complete all "Story Events" (Not all interactions contributed to the album unlocks, however i don't know which particular ones do. Maybe someone in the comments can help with this. http://dungeon-of-the-endless.wikia.com/wiki/Events).
• Win game with Sanitary Pod. (Was the last thing i needed to complete the album)
• Get to level 25 with Drill Pod.
• Get the "Dexterous" achievement (Kill each type of mob 50 times).

Tips:

• Max and Josh make a good combo for most runs.
• Wes' ability "Urgent Call" is very useful for finding and unlocking heroes. (Remember you can use science to refresh abilities instantly)
• Use the Armory Pod to unlock most of the "Story Events".

Here's a link to my album when i unlocked the achievement. Some album images are still missing, so i guess not all images in the album count towards the "Yearbook Editor" achievement. 

I didn't need these achievements to complete the album. Hope that helps.