DroneBL lists IPs caught in automated abuse: hacked routers, open proxies, botnets, and brute-force attacks. Unlike most blacklists, a DroneBL listing usually stays until someone asks for it to be removed.
Something on your network is compromised. Hacked routers are a common cause, MikroTik devices especially, along with open proxies and infected machines. Fix that first, or the IP will be listed again.
Look up your IP on DroneBL's lookup page and use the removal request link on the listing. Volunteers review requests; if nothing happens within about a week, DroneBL suggests asking on its IRC channel. Removal is free. Only the IP's actual user can request it, so on a VPN or shared network, ask your provider.
A DroneBL listing is often the first sign a device on your network has been taken over. Generator Labs checks your IPs against DroneBL and hundreds of other blacklists and alerts you by email, Slack, SMS, or webhook when a listing appears. Free for your first host.
Usually not. Most stay until a removal request is filed.
No. It's free.
The IP's actual user. On shared networks, your provider.