It can't be either deflationary or inflationary by definition. In both cases you are making a price prediction with which you could make a risk free profit if it held true. Whether you have to go long or short, you would in the end trade away the expectation.
Yes, it depends on whether economy is expanding or shrinking. In the first case it will be deflationary, in the second inflationary...
Yes, but then we are talking a movement around some level. Not a constant deflation or inflation.
I suspect the economic cycle in a bitcoin economy will be much less than we are seeing now. A lot of it is caused by the time delay between a central banks guiding indicators (gdp growth/inflation) and the effect of its instruments (money supply change). In aviation it would be called Pilot Induced Oscillation, plenty a crash is caused by that.