My Case is already dismissed and have received these 2 documents : “ORDER OF DISMISSAL” & “STATE'S MOTION TO DISMISS”. Are they sufficient for me to travel back to home country and come back to USA. Is this the “Court Disposition Letter”? And will there be any problems at Port of Entry, please confirm.

But for an official record,
What I will assume has happened, is it is a plea deal, you will be on probation at this point and once you complete the required community service, and/or fines, then the court dismisses the charges. The record on your criminal history will show this.
While it should not effect your travel, they will be able to view it as such

If the case is dismissed in Texas do u still get community service or probation?