I would for sure hire someone to finish the drywall ......i see so many people try this themselves and get frustrated and hire someone ....and could of cost less then what it will after they have spent 2 weeks working on it.

And FYI ....if not to far ahead i would glue the drywall on to walls with Dsa/20, Liquid nails or pl200 and just put 2 screws in the field of ceilings is all you need.
Will be less work for you or taper and less room for error especially if you are doing painted ceilings

Splatter is not as easy as one would think especially a true orangepeel but it easier then knockdown.... a regular small compressor will not do the the job properly ...it wont keep up...you will starting and stopping and will be very hard to keep it even. Pay the $40 or so dollars(whatever it costs down there) and rent a texture machine.
Mixture and gun setting and even spray is the key to what kind of texture you want? But dont forget another important step.....use the right primer/sealer....up here we use Synko Quickdry is the main industry product but others will use Hamilton
Im not a fan of the texture at all but easiest to to do for a beginner or DIY is sno-tex(popcorn as some call it)....something to think about