1) Yes, you can... but you will need to replace or re-fit the masthead casting with one that has sheaves in it. Normally, four sheaves, two aft, two forward—for the topping lift, main halyard, spin halyard and jib halyard respectively. Also have to add the exit slots for the four lines down on the lower part of the mast.
2) Lines commonly led aft on a sailboat include:
a) Main Halyard
b) Topping Lift
c) Jib Halyard—though not always necessary if the jib is on a roller furler
d) Spinnaker Halyard
g) First reef tack reefing line—I prefer to use a two-line reefing setup rather than single line reefing since I think it is faster and more secure.
h) First reef clew reefing line
i) Second reef tack reefing line
j) Second reef clew reefing line
k) Jib furling line
l) Asymetric furling line
You need to have the topping lift, main halyard and reefing lines in order to reef from the cockpit safely IMHO.
3) Rope clutches are better for lines that stay in the same position for long periods of time. Cam cleats are better for working control lines, like sheets. The best rope clutches in terms of usability are the Lewmars, and they cause the least line wear as well.
4) Winches go aft of the rope clutch. The line passes through the clutch and then around the winch... otherwise, you'd have to take the wraps off the winch and then tighten up the line again before closing the clutch.
Hope this helps