Hey man welcome too the forum!
There have already been some good posts here and I'll try to add a bit more information to help you out.
1: It can be normal to hit max rpm's when towing during the initial take off, but it can also be a sign that your propulsion system needs maintenance. Even though the boat only has 30hrs, it is over 5 years old and things deteriorate over time as well as usage. If you are experiencing cavitation (see answer for #4) then the boat will rev very high during hard acceleration until you get on plane. It all depends on what you are towing, how much weight and how many you are towing. I have the 155hp version of this boat and I can tow 2 tubes with full size adults with little problem or cavitation during take off. I have never tried pulling more than one skier, but depending on the weight and skill of the skier, it can take a bit of time to pop the skier up.
2: White smoke coming from the exhaust port at the rear of the boat is normal. These engines inject sea water into the hot exhaust to cool it so the exhaust pipes do not melt your boat. Doing so causes the water to turn to steam which exits the boat as 'white smoke'. Perfectly normal when the boat reaches operating temperature.
3: Beeping alert and hot exhaust is problem that needs to be solved before you use the boat any further. Ignoring this can cause expensive damage and may even melt parts of your engine compartment. It can be many things including, faulty temp sensor, blocked or partially blocked exhaust cooling system, propulsion system cavitation.
4: See this thread about how a jet pump works and cavitation:
http://www.seadooforum.com/showthread.php?4959-quot-How-a-jet-pump-works-quot&highlight=jet+pump+works
In a nutshell, cavitation is the jet pump loosing compression and sucking air. If air gets in there, you loose propulsion and the water/air mixture just spins around in there like a blender. Feels like a transmission or clutch slipping on a car, you give it gas and engine revs but no go. During cavitation, since there is very little propulsion, there is also very little cooling water being sent to your exhaust system which can cause it to overheat. Hopefully you can seen now how this is all interrelated.
If I were you, I would start by taking a close look at my propulsion system. Inspect the jet pump, impeller, wear ring, bearings, and drive shaft carbon seal. Any and all of these things could need replacement and would cause cavitation. There are lots of threads about this stuff so you may want to begin by doing some searching and reading for more info. You can also download the shop manual for your boat and engine to see how to diagnose these things and do the maintenance yourself. If you have a decent set of tools and some mechanical know how, you can do most of the maintenance yourself.
Good luck, let us know if you have any other specific questions.
