Living in Thessaloniki for many years (whole life) and being a writer (to be actually *cough*) myself, I will gladly assist in this task.
1) As for this one, there are plenty of apartments for renting in Thessaloniki if you are looking for a self sustained lifestyle, we can pick the appropriate place (of course that include showing you around places to shop at...and eat...when you're bored to cook).
If on the other hand you're looking for a hotel/studio to rent, which provide more assistance in....living... we can still find some opportunities, budget-wise.
2) For a stay that lasts many months, I would definitely recommend renting an apparent, in fact as I was recently looking for a friend, there are many available all years round for housing a person and many, many, many, scripts. But details of the desirable size, you will probably provide (this isn't euphemism).
3) Here I can only arrange for companies to do that, since my car won't fit many furniture pieces.
4) I will need your CV and general skillset for that.
5) Ah, this one would be the most pleasing task to take upon, tho I sort of mentioned it included in the "1" task. But it would be pleasing help around and maybe get to know a professional writer. (cause clearly myself I'm an amateur..for now..)