BronzeWomn
The middle pedal is used to sustain one note and is a little trickier to use than the other 2 pedals because one has to 'catch' the note at the right time (just after striking the key). If this is done right, the note or notes that were down and the pedal was pressed will continue to vibrate freely while all other subsequent notes will not. The dampers will come back down when you release the pedal.
There are different techniques for using the sustain pedal and it is a topic that can fill pages. One oft-used technique is to play a note or notes and right after that, press the pedal. You need to come up just before playing notes that change the harmony and then back down again into the new harmony. But that is a very simplified sentence and doesn't address all the nuances available. In general, follow your ears--change when it sounds appropriate. If you end up with a muddy sound, you're not changing in the correct places. I hope others here will add to this because it is such a big topic.
Sometimes, when both hands have the same note, I actually use a finger from both hands. Sometimes I only use the hand that has the note in the melody. Sometimes I only use the hand that is most conveniently placed as long as that doesn't distort the line. It all depends and again, use your ears and judgement.
I guess when you write 'fatchords' you mean chords that have a great overall stretch from inside to outside of the hand? Practice with a loose wrist and forearm, let the fingers spread apart--don't reach for the individual notes. You'll feel this goes all the way up the arm; remember to keep your elbow free. You might need to raise you wrist up higher than usual. Never force it, practice it frequently with a span that doesn't strain. Eventually you can try to extend the range.
I hope this helps a little.
