Forestay and halyard; I would say you do not want to have the halyard holding the mast up.
I usually tension the main sheet to pull on the topping lift before I tension the jib halyard.
Agreed. It's the same system that's used on the 18 (as well as all other furling Hobie jibs). Hoist the end of he boom up using the main halyard. Then pull in the main sheet blocks to pre-tension the forestay. Then hoist the jib and set the jib halyard tension. If you don't pre-tension the forestay, you will stretch the heck out of the jib luff or break the wire halyard when you sheet in the mainsail - the load needs to be supported by the forestay.