What should I convert Fescue into?

Most of the reason people use straight switch is due to the snow belt. Switchgrass lodges much less than other NWSG and will stand back up when snow melts. I agree that a field of straight switch is habitat neutral at best and having strips or pockets within that field would lead to the best wildlife habitat.
I don't think in most years you'll have a big problem with snow in Kansas, but it is something to be aware of. Ice storms will also flatten any grass planting, however switchgrass is the most likely to pop back up after the thaw.
The north/south layout of this place has made it tricky to hunt this year. Seems like the deer have been working the edges and have forced me to go in deep - my access hasn't been very good. Hoping I can get some consistent movement like this so I don't have to go in so deep.

My guess is they're using the edges due to your neighbor's ag fields being their primary food sources. Once you change that, they should relate to the security cover within your property. If you get a forestry mulcher out to grind down some ERC, you could have the equipment mow some access trails on the east and west side of your property to access stands.
It will be interesting to see if I can find some of the beds. I'm thinking there are some points they might bed on. If there's an elevation band, I should have a few places as the terrain goes up and down a fair bit.
Exactly. This is exactly what you should find, then enhance those spots.
That pond is a couple acres and would be good for this, but I need a west wind. It happens somewhat regularly, but as Angus pointed out, the thermals make it tricky next to the pond.
Maybe you can get an enclosed blind in down by the water's edge to protect from thermals. Could enhance the pinch point with a small kill plot along the water's edge? See my other responses in red, hidden in your quoted text.
I’ll probably do switchgrass screening along the roads, but for the cover in the thinned ERC, is there a seed blend you recommend?