Check out the H18, and if it is solid and good, buy it and then sail it, with or without wings. When you have figured out the basics of cat sailing, then ask yourself how 'hard' you want to sail, how 'dry' do you want to sail etc.
Once you upgrade to wings, Magnum or SX18, then you'll have to add the anchor plates (a minor structural upgrade) as noted above. Buy the kit from your local dealer. Lots of stuff on the Forum about this. Critical to do if you sail heavy or if you sail in chop or if you sail hard.
MAGNUMS are shorter and were welded. SX18 are rivetted are 11 feet long and are awesome, but not cheap. I found a pair in California, and the shipping alone to Ottawa (between Toronto and Montreal,) cost me $200. I was very lucky to find them, I had help, and these are very rare on the used market.
Pace an ad in the WANTED column of this forum, and CATSAILOR etc.
A Telo-cat is a windvane that sits where the bridle wires joins the forestay, and located there as you can get a stiff neck looking up to the top of a 28 foot mast to see the relative wind.
An Aussie halyard ring is a gizmo that helps some folks 'click' the head of the sail onto the 'hook' at the top of the mast.
Keep exploring the wonderful world of Hobie. There's lots of us out there who are happy to help.
1989 Hobie SX18 Sail # 1947
'Only two things are infinite, the universe, and human stupidity. But I'm not sure about the former.'