I have a few suggestions. I am near DC, so I know a few things that work in this area although I think your temperature swings are larger. First, I really love the wild look of the grass and the soft subtle shadings from gold to russet. It looks from a distance very lovely and a great transition from the lawn area to the woods. However, I think you are asking for a controlled wildness with little to no upkeep and no mulch. My instinct is that if you spread the low growing grass mix over that area, the more established grasses would beat them out. It would be patchy at best and you would have to weedwack anyway. Here are my suggestions. I think it would be lovely to plant that hill with daffodils -you would probably need hundreds - let them come up, then weedwack in early summer as the leaves of the daffodils die (don't cut beforehand or they will not store enough for next Spring). There is some type of attachment you can buy for a power drill/driver that will make the job super easy. The bulb forum is rather slow, but very knowledgeable. For summer to Fall, you would be stuck with what you have now. An alternate suggestion is to use cardboard/paper to smoother what is there and then plant perrenials with high sun/low water tolerance. There are lots of lovely hardy sedums and day lillies come to mind. I really love lavendar also. Maybe some bushes for height/erosion control. For that space, it would be a LOT of cardboard! The reason I suggest cardboard is you can use long garden staples to keep it down. It would also become dirt and need to be renewed to continue suppressing weeds. Big project every few years and to make it nice looking, I would layer fall leaves or mulch on top. Look up lasagna gardening for more details. Another choice is to buy a meadow mix, throw it out there and let the plants duke ii out --survival of the fittest! Hope my ideas are helpful! I am not so much trying to give exact instructions as to point you towards possible paths where further research can help you reach the best conclusion.

I'm not sure what kind of tree that is. With some trees, having the roots that way is normal and healthy. Some trees suffer if their surface roots are buried so research that before laying on a lot of soil. The water coming off of the pavement has a lot of velocity. Porous pavement is very green but expensive. Conceptually, look up things like french drains and water bars. You can also surf Erosion Control magazine for free on the web. Also check websites for Ohio's department of transportation and department of environmental protection (or whatever the equivalent departments are in Ohio). Here is a link that might be useful: Erosion Control magazine

I agree with dottiecarrano; Let the weeds be! :) I live in Eastern KY as well and completely understand how difficult it can be living backed up against a hillside. However, I have found that trying to live in harmony with the hillside tends to work much better than battling against it. Why rid the hill of its natural vegetation just to replace it with something that may or may not like it there. The weeds might not be the prettiest thing to look at, but they're definitely better than a dirt wall (which is all you will continue to have if nothing else takes to it). I mean, if you want invasive you could bring in some kudzu or something (goodness knows we have enough of that around here), but I don't think you want to do that... lol But yes, all those sprays are creating toxic runoff and, if anything, are counterproductive to what you are trying to achieve. We've got some really pretty "weeds" here in EKY; Let 'em live. :)

It is impossible to keep critters from passing through a planted bed, but so long as you don't cultivate plants that pile up thickly with plant debris, they would not be inclined to make it a home. I hope it is just camera tricks, but the walk at the back of house appears to be sloping toward the house. If true, that would be worth fixing, as surely, a large amount of water will come off the hill at some point. At the end of the flumes, it appear that gravel is piled above the flume outfall height. This is going to create somewhat of a dam. It will drain out at the end of a storm but will hold some height of water during a storm when there is heavy flow. I would plan to be out there with an umbrella observing exactly what's happening in order to know if something needs attention. Do you need to be careful of wildfires? If so, see if the local municipality has a list of recommended groundcovers. Do you need shade at that side of the house? Some tree forms along the hillside would help hold the soil in place while not blocking the view. The steps to the top (nice wide ones) sound like a great addition if there can be a special viewing spot created there. What flanks your property on the other side of the hill? As one example, a tall bamboo forest (such as Oldhamii) with groundcover below, would look great. It looks like you have enough room at the end of the house for a more or less linear patio. One with some boulders could look nice.