Just attach a piece of fuel line and let it hang free under the engine. In a 2-cycle engine, the crankcase is pressurized for proper fuel flow through the engine. In a 4-stroke, the crankcase is not under pressure, and needs a vent line. You'll get some oild drippage from the vent line, hence the reason for attaching a tube to channel the oil "overboard".

4-strokes get their lube from the oil in the fuel, just like a 2-stroke. Both synthetic and castor oil have a much higher flash point than nitro and methanol, so they don't burn with the fuel, but gets pushed past the piston ring, and seeps by the valves through the guides; the oil that makes it past the piston lubes the rod bearings and eventually gets to the crank bearings and up to the cam drive; it's this oil that eventually gets dumped through the breather vent.

You can use the same three-line system with a 4-stroke as well as a two stroke.

I am not familiar with Duraglow 5, can't answer that one. Saito recommends at least 17% oil, as a castor/synthetic blend, and saitos run well on up to 30% nitro content, although 15% is plenty for normal flying, and all-synthetic oil seems to work well. I'm using 15% nitro, all synthetic (17%) Cool Power in the 5 Saitos I own, and haven't had so much as a second's problem.