Use good quality seed compost, I find john innes best, keep them at 64-70deg f until they germinate, you can then reduce the temp a little, they will probably take 3 or 4 years to reach flowering size {maybe more}

Ja, I would put Stelitzia seeds in good fertile soil and at the temps Derekm has said. They will need repotting over the 3-5 years that they take to flower as they grow to about 4-5 foot high and pretty wild. In South Africa they are used in a lot of road sides and in borders in developments - the soil is red clay but is fertile and if raked pretty light (cause of less frequent rain than here). They have rhizomes so a loose sand and bark mixed soil would be good to let them grow.

Remove the orange beard on the seed. It has something in it that will inhibit germination. A soak for 24 hours will help, also. Then it takes about a month to germinate, sometimes longer. I have the nicholai, and it has been almost 7 years with no flower. My regular ones do best in well-drained, sunny soil.