If you feel adventurous, v1.5 already has those building abilities. (In fact, ND1 always had most of these functions since v1.0.)
You can try out sliders today, if you want.
While you cannot upload/save a custom calculator today, you'll be able to do so with the v1.6 update. The next update, 1.5.1, is going to re-enable tab hiding on iOS 7, but it won't define new keys. So there'll be no need for you to Restore Calculator. That is, you can safely update, you won't lose your custom key assignments/menus.