ditch

I have a piece of rolling land and I am at a point where I am considering filling a low point on the land (pictures below). What I am trying to determine is what is best to fill it with. I have a variety of materials handy. Everything from dirty fill(loam, twigs, small rocks, roots), to regular...

I have a Ditch Witch A420, that is set up on a 3 point hitch rig with a pto pump. My problem is I blew the seal on the boom cylinder and can’t find a reseal kit or part number for the cylinder. Thought someone else might know.

We have a property that has quite a steep gravel driveway. I'd like to redo the driveway but that is a future project. Right now I'd like to keep it from washing away. I have an L3901 with loader and backhoe. The ditches on the side are filling in with debris and sediment. What is the best...