Whoa, that sounds like an interesting (probably scary) story about the dolphins.
The fact that you have already started wakeboarding and waterskiing I would imagine you can handle flying a trainer kite without any big problem. But of course you should start out in lighter winds with no more than a 3m kite and - just like with water-skiing and wakeboarding - LET GO of the bar IMMEDIATELY if you encounter any out of control situations.
Once you are comfortable with the trainer kite and have solid kite control skills you will be ready to fly a larger kite, which will probably place less tension on your arms than a powered up trainer (without a harness). I discourage beginners from using a harness with a trainer kite (flying hooked in) on dry land unless there is direct supervision by an experienced kiter/instructor. However flying a trainer kite with a harness is a good thing to experience at some point so that you can get the sense of being hooked in...and then you will see how little "work" your hands and arms are required to do when steering the kite - since the harness will take up 90% of the load.
I imagine there is someone in the Chi area that can give you some basic pointers on the trainer kite. I would be happy to give you a primer but I am over in MI - if you come this way feel free to contact me.
Another really good thing for you will be to try snowkiting before you try kiting in the water. You should still get a good set of lessons for this, but most people can succeed in getting some rides the first day on snow, whereas it may take several days on the water with ideal conditions. Hopefully Mother Nature will deliver a better winter this year...fingers crossed.
If you havent already figure this out - a goood way to condtion yourself will be to do some light rowing/pull downs exercises ( multiple angles) at the gym or at home if you have a machine. Light weights and lots of slow reps would pobably be best.
Another good resource for you is to visit the website of Dr. Sarah Ellis who has many kiteboarding/wakeboarding specific exercises for conditioning and rehab purposes. If you like what you see I encourage you to support her efforts and purchase her on-line training manual. I think it is a pretty good value.http://www.perfectlyfitonline.com/