G'day Neo,
You'll be on a winner with a 250mm Dob. Thousands of deep sky (and solar system) object's will be visible many showing breathtaking detail. As for eyepieces get the best you can resonably affoard. Also I personally dont rate barlows its just more glass between the object and your eye and are a bit awkward to use with an un-driven Dob.
I hope I have been of help
