Paul,
Congratulations, so far.
As for aluminium and corrosion, I have used aluminium in the 60-series; 6060, 6063 or 6082. These are corrosion resistant enough without any treatment. However, it may be an idea to paint an aluminium mast as it tends to stain the sail black in that position.
The diagram below shows basically how I tie on the halyard’s slingpoint on the yard these days. The sort of lashing is not critical. The thing is to remember to fit (tape on) that stopping line to the underside - before starting the lashing. The stopping line prevents the slingpoint from creeping any more - I only fitted it a couple of years ago. The stopping line is simply tied to the first available little webbing loop at the head of the sail. The forces in it is next to nil. It is only there to ensure that the lashing binds or lock itself.
For the batten parrels I have used a similar, just smaller version. The stopping line there is just a piece of twine, which I stitched to the batten pocket. In other words; those ‘stainless’ hoseclamps have been removed. They had started to rust. The only hoseclamp left, I think, is the one on the boom in front of the topping lifts.
Good luck!
Arne
(Full size diagram at Arne's sketches, section 7-39)