R. banksia banksia

I am obsessed with my banksia (white double) and have some questions about some of the quirks of this rose. For one, is it normal for the canes of other banksia bushes to climb up trellises and such completely thornless yet when the canes reach a point that there is at least 5 inches of vine without pressure stimulus (touching anything), large amounts of prickels begin to form? I’ve heard that its hard to germinate their seeds, any ideas? Any ideas on the odds of a cross I’m being hopeful for between banksia and black jade? Thanks for ya’lls opinions.