Will 2Do show iCal events and tasks together in the same list?

No. You cannot mix tasks with calendar events. Events and tasks are fundamentally different types.

2Do does provide a separate Calendar Events view alongside your tasks:

• iPad — use the right calendar/editor pane when it is visible. In a narrow iPad window, use the same swipe-left Utility Panel gesture as iPhone.
• iPhone — swipe the task list left to reveal the Utility Panel, then tap the Calendar Events button in the bottom toolbar next to Nearby/location. This view is not available on Mac — use your calendar app for event planning on the desktop.