[whpalmer4]

Yes, OmniFocus will create groups as needed.

Start any time
Started more than a year ago
Started within the last year
Started within the last 6 months
Started within the last 3 months
Started within the last month
Started within the last week
Started yesterday
Start today
Start tomorrow
Start within the next week
Start within the next month
Start within the next 3 months
Start within the next 6 months
Start within the next year
Start more than a year from now

As for the second part of your question, you asked to see all the available tasks, grouped by context and sorted within those groups by project. That's what you received. By default, tasks are always available, without any action required on your part. What makes a task not available is one or more of the following:

task is completed
task is in a sequential project or action group, and is not the next action
task has a start date assigned which is in the future
task is assigned to a project or action group which has a start date assigned which is in the future
task is assigned to a context which is on hold
task is assigned to a project which is marked dropped
task is assigned to a project which is marked on hold
task is assigned to a project which is in a folder which is marked dropped