Re: Rookie boaters nervous?
Good advice here--coming from half a century of boating, mostly in old ones in salt water!
Philster said it well, that even the experienced boaters are nervous about this or that, but it can be overcome with confidence in your equipment, or confidence in your skills to fix it.
Robert makes a great point to stay aware of your surroundings, which means weather, tides, other boaters as well as your equipment. Are all your lines in? Loose items secure? Look back every now and then so you have landmarks to get home--even after dark.
You can't beat experience. Just spend lots of time with the boat. This may make you feel better: those who buy old boats that need work, and do the work, know their boat better, and are better boaters, than the guy who buys one brand new with no problems. Because the bottom line is, "if you have a boat, you have a problem."
You mention your guages. Never rely on any of your gauges and gadgets. Alarms and sensors might work; a guage might be accurate, a GPS might help find the way, but all of them will crap out on you. While you should carry a cell phone, it is the most fragile least reliable thing on the boat, so proceed as if you dropped it overboard at the ramp. Which you will. So if you disregard those things in the first place, you will have a better day, than worrying if you are overheating and the guage is broken. Likewise, some alarms, etc. are over-sensitive and you have to discern that--just like the smoke detector that goes off when the roast is done, doesn't send you to call 911 and evacuate the house.
However, lack of confidence takes all the fun out of boating (which what most of us want out of it). So first, gain confidence. Any experienced boater will tell you, that once you loose confidence in a boat, you won't want to use it (worse is when your family looses confidence). This is why I suggest new boaters not buy the cheapest rig; it is worth it to pay for reliability and you can only get reliability by paying for it.
Tough thing about boats is that the tiniest thing can be fatal and the seemingly biggest thing harmless. A pinhole can sink a boat; a leaf on a drain hole can hold back 30 gallons of water.
Finally, take risks. Learn what your boat, and you, can do. Find the edge of the envelope. Don't be afraid to push it. Get through a hairy ordeal and you will be stronger for it.