Haha, it's part of the fun to discover the stuff but it's good to have some kind of guide :D Thanks for detailing all the information :)
The weird keys (like , and so on) are for users who happen to use a Dvorak Keyboard :D
The 100% music and sound thing will be changed in another update, so that it is saved - and there will be more options available (50% and so on).
More languages will be added soon :) (Dutch is the next one)
The Hardmode is playable after you beat the game once :D
I will change the erase savestate button and give it a: "Are you sure, yes, no"!