David has good advice. A couple of things you should know about NWC2's implementation:
1) Pedal up|down applies to the midi channel, not just to the staff. If you make both the upper and lower grand staves say, channel 3, the pedal points on you put on the lower staff apply to the upper one. Try changing to a cello to hear this clearly.
2) Two pedal downs do NOT make a pedal up! It is common to see a pedal down, then another pedal down, without a pedal up. The pedal up is implied. Not so with NWC2. You must put in a pedal up (it can be invisible). Make sure there is a pedal up at the logical end of the piece or you will get the dreaded "stuck notes".
As to you other questions:
The left pedal on a piano is usually called the "soft pedal".
This is accurate enough for most pianos. Some lower a strip of felt between the hammers and the strings. Others move the entire hammer mechanism closer to the strings. A good piano will shift the entire keyboard about 1/8" (usually to the left). You can see and feel it move. On this type of piano, "soft pedal" is a misnomer. "Una corde pedal" is correct. The upper keys normally hit 3 strings. Shifting the keyboard causes the hammer to hit only one, hence "una corde" (Italian for "one string"). This produces both a softer and "thinner" sound.
The usual marking for this is una corde or una córde in Staff Italics below the lower Grand Staff. The "pedal up" indication is: tre corde (Italian for "three strings"). Like the damper pedal up, tre corde is often implied. Any increase in dynamics means a release unless an explicit release is noted. Debussy wrote a piece calling for una corde even in sections marked forte.
The center pedal is usually called the "sostenuto pedal". Some pianos don't have it. On others it does nothing! On my piano, it lifts all the dampers from great C down. On a good piano, it sustains just the notes that are down when it it depressed. Any notes played after are normally dampened. This is no standard notation for this. Sometimes it's use is indicated in a footnote. Debussy's "Claire de Lune" and Rachmaninoff's "C# minor prelude" clearly need it, but there is no indication in the music. Here's an example from Elgar:
!NoteWorthyComposerClip(2.0,Single)
|Text|Text:"©1905, G Schirmer"|Font:PageSmallText|Pos:12|Placement:AsStaffSignature
|Text|Text:"Elgar - Salut d\'amour"|Font:PageSmallText|Pos:16|Placement:AsStaffSignature
|Clef|Type:Bass
|Key|Signature:F#,C#,G#,D#
|TimeSig|Signature:2/4
|Chord|Dur:8th,Staccato|Pos:3,5
|Chord|Dur:8th,Staccato|Pos:3,5
|SustainPedal|Status:Released|Pos:-9|Wide:Y|Justify:Center
|SustainPedal|Pos:-15|Justify:Center|Placement:AtNextNote
|Chord|Dur:4th|Pos:-11,-4
|Text|Text:"73"|Font:StaffBold|Pos:11|Justify:Center|Placement:AtNextNote
|Bar
|Dynamic|Style:ff|Pos:12|Justify:Center|Placement:AtNextNote
|RestChord|Dur:8th|Opts:Stem=Up,ArticulationsOnStem|Dur2:Half|Pos2:-12^,-5^
|Chord|Dur:8th,Staccato|Pos:n-1,4,n6|Opts:Stem=Up,Beam=First,ArticulationsOnStem
|Chord|Dur:8th,Staccato|Pos:-1,4,6|Opts:Stem=Up,Beam,ArticulationsOnStem
|Chord|Dur:8th,Staccato|Pos:-1,4,6|Opts:Stem=Up,Beam=End,ArticulationsOnStem
|Bar
|Chord|Dur:8th,Staccato|Pos:-3,1,4|Opts:Stem=Up,Beam=First,ArticulationsOnStem|Dur2:4th|Pos2:-12,-5
|Chord|Dur:8th,Staccato|Pos:-3,1,4|Opts:Stem=Up,Beam=End,ArticulationsOnStem
|Dynamic|Style:f|Pos:13|Justify:Center
|Chord|Dur:8th,Staccato|Pos:-9,-2|Opts:Stem=Up,Crescendo,Beam=First,ArticulationsOnStem
|Chord|Dur:8th,Staccato|Pos:-10,-3|Opts:Stem=Up,Crescendo,Beam=End,ArticulationsOnStem
|Bar
|Dynamic|Style:ff|Pos:13|Justify:Right
|SustainPedal|Status:Released|Pos:-9|Justify:Center|Visibility:Never
|SustainPedal|Pos:-15|Justify:Center|Placement:AtNextNote
|Chord|Dur:Half|Pos:-11,-4^|Opts:Diminuendo
|SustainPedal|Status:Released|Pos:-15|Justify:Center
|Bar
|Chord|Dur:4th|Pos:-8,-4|Opts:Diminuendo
!NoteWorthyComposerClip-End
You just can't do it without a sostenuto pedal!
In this case it would be pressed just after the 8th rest in measure 73 and released at beat 2 of the next measure. Midi-wise, you have no problem; the computer doesn't care how far the notes are from each other.
Probably more than you wanted to know, but ...