User Input

I am trying to built a task generator where there is an existing list of task and the user inputs their free time and the app spits out a tasks that can be accomplished within the allocated time.

Do I need to create a separate spreadsheet to capture the user’s inputted free time?

How to do I pull the user’s inputted free time as the allocated time to generate the tasks?

Besides using a SELECT() expression, is there an easier way to use the user’s inputted free time to generate a list of task?