Well, I'm not sure how to disassemble the front free-wheel; the crank came apart easily enough, but I want to take the FFS apart as well to clean and re-grease the bearings.

I'm also still not sure; provided I wanted to convert it to single speed, would I have to buy some special rear cog or would any aftermarket thing on amazon work? After hearing that the rear cogs need a special tool that isn't the typical Shimano to take them off, I'm concerned about their compatibility with standard bike technology.