Howdy webster,
We use the constant TribeEvents::POSTTYPE throughout our code to refer to the tribe events post_type. You could also just use the string 'tribe_events' since it is doubtful that constant will ever change in a future version.
You might find the function tribe_get_events() helpful. It makes it much easier to select events by a date range, instead of by the date they were posted. If you need a WP_Query object returned, set the second (optional) argument in tribe_get_events to true.
Does that make sense? Will that work for you? Please let me know. Cheers!
– Brook