I found at least one non-profit that has a website (updated link) that contains statistics based on specific country. I don't know how accurate they are because many attacks are probably still unknown. I don't know if you can download their data as a database, but I think with finite data points, you can reconstruct the data set yourself.
For the optional stuff:
- Demographics: are sort-of there (Militants killed, Civilians killed, Unknown killed, Target organization)
- Reason for attack: you may have to dig up media stories for specific attacks and then join that info with the data set
- Organization/country piloting the attack: this website has organization and is sorted by country.
I would start by reaching out to this organization (or any other similar ones) and ask if you can take an export of their data set. They use a Creative Commons license, so they encourage non-commercial use with attribution.