How To Free Up Memory On iPhone 6

Two questions:

1. On this screenshot, it shows that I have 2.25 GB (1119 photos), but I really only have 28 photos on my phone right now. How do I know where the rest of the 1,000+ photos are, because I have not synced any from my iPhoto or elsewhere to this phone? I have not used my iCloud at all, so nothing is synced there as well. I would like to free up some space because I really do not have that many pictures on my phone.

2. Does anyone know what goes on "Other"? It's not the music, apps, ibooks, tv shows, podcasts, movies, etc. It's 3.72 GB of space that I would like to manage as well.

Appreciate any help. Thank you!