The Reader gate has inputs on the bottom and outputs on the top, left, and right sides, the reader gate reads the signal strength it gets from the input and via gui the user can configure at what signal it will begin outputting a redstone signal, it is effective 15 long redstone dust in a signal block.
It could be used in many ways with so many mods using blocks that emit a redstone signal strength, and the player having to run a long string of redstone dust in a other wise compact build just to automate a litall botania setup.

I am sorry if i did not enplane it vary well i did the best i think i could, if there is something that is not clear or you would like clarification on pleas let me know i really think that this would be vary use full.

So... A comparator ?

No a comparator gets a redstone signal from a inventory (only a example) and then outputs a signal strength dependent on how many items are in that inventory, The reader gate would take that signal and when the strength of that signal reaches a specified strength (specified by the user) it will output a redstone signal strength of 15.

A example of how this could be used is with a daylight sensor, you cold have it so the reader gate input is up against the daylight sensor and when the signal strength output by the daylight sensor reaches (for example) 9, the reader gate will emit a signal stranger of 15 and you could place a redstone lamp adjacent to one of the reader gates outputs, this set up would let you have a lamp that turns off when it is night time and on during the day, using this setup would only take up a 3 block space.
Or there is the current way of doing it witch is to have 9 redstone dust placed on the ground leading to the lamp, the minimum size of this would be 11.

I hope that this helps :)

No, this can easily be done with a bus converter. I know there isn't documentation for it, will add it soon.