This is a 1 Tonner! The F350, besides having a higher GVWR, has a longer wheelbase - a 3/4 ton has a 8 foot bed, a 1 tonner has a 9 foot bed, standard cabs of course. Fords are fine, as long as you have the radiator re-cored with a thicker core.
It won't hurt idle or improve it either. It might give you a small boost in part-throttle mid-range performance. But it will sound different. I like the sound of 2 separate duals, but some other guys like the sound of duals with an H pipe. I doubt you will consider the effort worth it.
6 to 8 OZ in 6 months is considered a leak? I doubt lack of sealant by itself would cause a leak into the oil. What COULD be the problem is one slightly loose head bolt under the valve cover could have a tiny steam leak. Another potential area, if you have a V8 and not a 6, is the water...
Your best bet are Deep Cycle batteries. The new type batteries may have more total Cold Cranking Amps, but they don't last long, whereas Deep Cycle batteries can crank an engine for quite an extended length of time.
That's is exactly right - they have more total Cold Cranking Amps, but like you said, it doesn't last very long. Deep Cycle batteries are made the old way, and are much better in my book.