The global font size of the output file can be changed with the font size setting on NWCTXT2Ly
If you're planning to make a LilyPond book, you will need all the individual LilyPond files in one place (to make it easy). However, if you name the staves from (say) two songs as "Bass", then these will be both be called Bass.ly. To overcome this, you can give them Part Names, like SongOne and SongTwo - the two files will then be called SongOneBass.ly and SongTwoBass.ly and can both be put into the same directory.
As far as I'm aware, Noteworthy only supports a single type of grace note, whereas LilyPond supports a range. For a given song, you can select whether grace notes will be translated as grace notes or acciaccaturas. Grace notes work better where the note is already within a slur, since LilyPond does not support nested slurs.
Page and Line Breaking
By default, LilyPond organises line and page breaks by itself. However, you can force a line break by putting ##\break as hidden text on one of the stave. You can force a page break by putting ##\pageBreak as hidden text. Even if you do this, you may still find the LilyPond breaks where you don't want. To force it only to use manual page breaks, select the "Use manual page breaking".
Other LilyPond markup
Any markup that you can put directly into LilyPond you can enter using the "hidden text starting with ##" feature. For example, I frequently use:
No doubt there are many others. Be careful that most markup that requires an apostrophe will not work, since the apostrophe is "escaped" with a slash during translation.
To export tremolo notes, mark the start of the tremolo notes with tremoloOn as hidden text (note the capitalisation) and the end of the tremolo notes with tremoloOff. The notes in the Noteworthy score should be appropriate for the time signature (e.g. 4 crochets per bar for 4/4 time) and these will be notated as 4 notes with semi-quaver tails in the LilyPond score.
Different lyric syllables on each verse
If you have lyrics where, say, the first verse has a single syllable fitting a crochet and the second has 2 syllables fitted to 2 quavers, it gets a bit complicated :-(. I've solved this by using multiple voices with music in each voice that are normally identical, only varying where the difference in syllables occurs. The frst verse lyrics go on voice one, and the second on voice two. Rests in voice 2 are hidden. We then mark voice one with the special hidden text "multiLyric". This suppresses warnings from LilyPond that there are clashing note stems - we know this, since the music is the same in the 2 voices! This method is illustrated in the image/.nwc file below - though remember that if you're typing this in rather than downloading it, you should layer the 2 staves. I've separated them for clarity.
(The Mikado strikes again). In Lilypond, we get the result below:
Which is what we wanted.
Just occasionally, LilyPond takes an extreme approach to fitting a slur to the notes. An example is below:
I wanted to be able to control this, and LilyPond does have two mechanisms to allow finer control. I selected the simpler - over-riding the start and finish position. To do this, add setSlur(x,y) as hidden text just before the slur. X and Y should be numbers specifying how much the start and finish should be raised. You should also add setSlur(0,0) afterwards, to reset the slur position. Using setSlur(6,4) with the above music, I got:
with the result to the left being the adjusted slur and the one on the right the default. The one on the left works better for me.
It only remains to mention that the User Tool, NWC2Ly implements all the "within staff" features mentioned about NCWTXT2Ly.