As far as the first question, it's been a few years since the tile layout has come and gone in Nickel
.
There's a patch to remove the bottom row, but there's no silver bullet to "pin" specific stuff on the homescreen.
In KOReader's case, the point is pretty much moot now, though, since you can have it in the Main menu via NickelMenu (bundled w/ the OCP), which I'd say is even better than a pinned book.