Welcome TO the Dark side! Of extreme sailing!
I'll try and answer some of your questions.
Any good 3/16in line would be good for the halyard, less stretch is better.
Any good screwdriver will work in the mast base. It comes with a pin that can have a ring on both ends so it son't pop out. I use the pin with on end without the ring, it never pops out.
The harken should be good for a long time, it probably came with it. The barber hauler is pictured in the online manual, and on a thread here, aobut the 4-way jib system.
With the mast positioned as you say, It should be NO prob stepping it.
Good sailing,
Todd Bouton
N6.0na +spin/snuffer