RE: ff sting?
I use FF on all my selfbows never had a problem. Of course self bows are one piece of wood and not glued together which is the real concern. I would think your bow is setup for it but without know I would be carefull. Like others said it isn't worth it if your not sure.
I'm no string expert but a padded look Flemish twist string isn't to hard on the tips. And there are some good string materials out thier besides FF.