How sure are you on that detail? I think medusa was able to create 100 accounts on a single ip within quick succession.
So I'm not sure what the limit per ip per x amount of time is in terms of creating accounts before getting blocked.
Osbot is still very active. You can gauge how well a script works from reading the script's thread or asking for a trial.
As for ban rates this site works:
http://www.osrsbanrates.com/
I will def be using it. So much easier to play in bed and if you go somewhere where you'll be bored for a few hours then you can just play way easier than bringing your laptop.
Is there a reason you tick the option on in the first place?
If you leave it off it will never be active on future clients and thus you won't have this problem.