Tutorial island is a heavily botted place, so expect to have a hard time botting there.
The chance to get banned usually depends the script and the place where you bot, i usually run my bots on 2 accounts at the same time on the same ip.
The lenght of the botting sessions depend on which skill and place. After some trial and error you will find can find scripts that run for hundreds of hours on some places and get you instantly banned at some others.
Don't bot on heavily botted places for many hours. Be innovative, try new configs and take time to experiment.
If you are buying a script look at the scripter's rep and the frequency of the updates in each thread. Frequently updated scrips will get u fewer bans.
You WILL get bans, but that doesn't mean you can profit on the accounts after all, even if they end up banned. Don't bot on accounts that are worthy to you.
Bot on many accounts, and rest them for a couple of weeks after the bond expires.