Whew...slow down boy!
Solo on a catamaran means that you need something 18' or less. Less length typically means less weight (sometimes) so shorter should be easier to right from capsize solo. There's a ton of these out there for less than $3k. The important thing to consider is bouyancy if you seriously intend to sail with multiple people on board.
Solo mast stepping - not really a big deal but it will require some practice. You can usually find someone to assist with the more critical moments instead.
I think the Hawaiian system is a loose, large diameter, bunji that resides under the trampoline on each side of the boat. If capsized, you grab the bunji and pull it out to it's extents while you lean out to right the boat. It really offers no advantages over a simple righting line other than speed. A righting pole, like Rick's system, gives you more leverage and ability to right the boat solo.
Not many reefing mains available for catamarans. We have a huge amount of control over sail shape and can sail in a very wide range of wind conditions as a result. However, roller furling jib does come in handy if you are sailing solo. Any boat can be upgraded to roller furling for about $300 (pricing varies depending on quality). Hobie 18s have always had roller furling jibs and may be a consideration. Most other boats offered from the factory with standard roller furling are F18, I20, ....gee. cant't think of anymore.
Wings are nice. but you're right that they are expensive. Hobie 18sx has wings (not the standarda TheMightyHobie18 mind you) and the Hobie 17. They can be a drag (pun intended) if you fly a hull too high - hence most of the modern constructed boats do not offer them.
Difference compared to a dingy...there's upwind, downwind, reaching and that's all the same. Sail trim, tell tales, etc. no different. The two biggest differences you will find on the catamaran are A) speed B) fun! Seriously, if you understand the basics, and understand the nuances behind righting a capsized catamaran (do a search on this forum), it's a piece of cake. Always keep in mind at every moment what you will do if you suddenly get overpowered because it happens quickly on a cat. For now, think about it as simply: Do you steer left or right?
The Hobie 16 is a good boat as is the 18...Nacra 5.2, Hobie 17 (primarily solo), Hobie 18, Nacra 5.5, Inter 17, Solcat, Supercat 17....the list goes on and on.
