1500 to 2500 words.
As for length of completion, it varies. I like to take my time curating what I want in the chapter.
I try to get rid of the 'fat', repetition, unnecessary sentences, plot holes, odd sounding paragraphs, etc.
Of course, I can also write 4000 words worth of garbage, just like anyone else. It's the editing and future planning of the story that take most of my time.
So...time-wise. 8-hours for a chapter at a state that's probably acceptable for publishing. And countless more hours in edits.
Let's just say that I don't publish a chapter immediately after completing it.