You don't need a mast stepping link, you can just get someone to hold the bottom of the mast in the cup. Just make sure that they hold on tight and push donwards.

Imagine that the mast is a beam with the person raising the mast as a pivot, if the person holding the base of the mast lets go, the mast pivots around the person raising and the top of the mast will crash down pretty quickly. I personally don't use a mast stepping link as it is so much quicker with someone holding the base of the mast. Just make sure that they hold it well.

As for your main halyard, you will be able to raise the sail with a rope halyard, however you will not be able to lock the sail into the hooks at the top of the mast.

The wire halyards have a sleeve that has been crimped onto the wire at the right place so that when you raise the sail, the sleeve locks into the locking thing at the top of the mast. This then means that when you tighten the downhaul (and you put a lot of force on the downhaul), the tension is not running all the way down the halyard to the cleat on the bottom of the mast.

If you're taking the boat out in light winds and don't need a flat sail (i.e. lots of downhaul) then you should be OK with the rope halyard, however if you're sailing in anything over a force 2 then you will want to flatten the sail and you will need the lock the sail into the mast.

For an idea of the force that the halyard would be under, look at the way the mast bends and think how much force it takes to do that. That's why a wire is needed!