If the fonts are not listed in the .properties file, it seems they are still not in a compatible format. Did you try to convert them with a mentioned above Python script?

Q2 more debug info will be available in forthcoming PD4ML v4
Q3, Q4 it is possible. http://pd4ml.com/examples.zip contains chinese_ttf sample, which illustrates how to do that.

See also http://pd4ml.com/cookbook/pd4ml_pdf_true_type_fonts.htm