The script allows you to select the location of where the bot will stand during the dream. The default location is south-west and you're only able to get attacked by 1 monster there. To answer your second question, the bot has a rapid heal flick option you may select and it will keep you at 1 hp.
How it works is, there's a set timer in RS that regenerates your HP every 60 seconds, thats why you gain hp automatically after a certain amount of time, by flicking rapid heal it will reset this 60 second timer to 0. Which in essence keeps you at 1HP. You will need level 22 prayer to use this.
If you don't have 22 prayer or don't want to use rapid heal flick, then the bot will use the rockcake to decrease your health whenever it regenerates past 1 HP.