I'm not an expert but...
1) I would NOT fix the end
2) I would simulate te bearings with bearing fixes. The first hinge fixing will support all the radial moment. Also will avoid any axial displacement.
3) You have two moments: one rotational and one..." bending moment", I don't know how to say.
When you speak about remote force, I suppose you are asking about the bending moment produced by the radial force.
If I understand you question, yes, remote force do apply this moment.
4) Yes, you should know the torque in each sprocket, in order to get a realistic result
5) What you call Y direction? Axial direction?
Too problems in one question. I would try to simplify the questions... specially if you expect to get answers
are the restraints ok? > they are a good first shot, i would recommend writing down what you think the assumptions are relative to them and what influence you think they will have on the results. bearing fixtures would be another option.
remote force apply moment > don't know what you mean here. it is a force not a moment. it will apply a load.
sprockets > it depends on the goal of your analysis. if your analysis goal is worst case where they are all locked up, you could apply a fixture where they are.
17mm displacement > what are you expecting?
what i'd recommend is starting off with a description of the application and the loading in the real world rather than a description of your setup. without the context, it can't be measured