WIRING: It's like Christmas lights … once you get a good power source you can really go crazy. I guess that's one of the reasons I've never added a power grid to one of my boats. Sure as I do, I'll have dash lights, bow/stern lights, and an 18" subwoofer (though a pair of 10's would probably work just as well). Once you are set up with a 12 volt system, anything that will connect on a go-boat will now connect in your row-boat. Those are scary possibilities indeed. You'll need to keep the battery stationary, as dry as possible, and make it easy to get at for removal and recharging. The easiest choice would be to mount it in the front hatch area. The battery is actually pretty small, so you won't need a lot of room.
Commercial and naval fathometers of yesteryear used a strip chart recorder where an advancing roll of paper was marked by a stylus to make a permanent copy of the depth, usually with some means of also recording time (Each mark or time 'tic' is proportional to distance traveled) so that the strip charts could be readily compared to navigation charts and maneuvering logs (speed changes). Much of the world's ocean depths have been mapped using such recording strips. Fathometers of this type usually offered multiple (chart advance) speed settings, and sometimes, multiple frequencies as well. (Deep Ocean—Low Frequency carries better, Shallows—high frequency shows smaller structures (like fish, submerged reefs, wrecks, or other bottom composition features of interest.) At high frequency settings, high chart speeds, such fathometers give a picture of the bottom and any intervening large or schooling fish that can be related to position. Fathometers of the constant recording type are still mandated for all large vessels (100+ tons displacement) in restricted waters (i.e. generally, within 15 miles (24 km) of land).
PERMANENT INSTALLATION: I say an installation is permanent once you start drilling holes. A permanent installation will require you to provide power/wiring, physically mount the transducer, and mount the fish finder itself. A few years ago, these things were a lot tougher to do - similar to baking a cake from scratch. I don't like the notion of "trial and error" when I have a drill in my hand. But now that our sport has become more mainstream, products are being offered specifically for kayaks, and fish finder installation can be so easy, even Betty Crocker could do it.
Bait: If you're not using live bait or cut bait, you'll want to use artificial bait or lures. Most artificial lures resemble the type of bait fish or other food, such as worms or shrimp, that the fish you're trying to catch normally eat. These artificial baits can be scented and have metal spoons attached to them or be painted in metal flake to reflect light in the water. Other types of bait include jigs and jig heads, spoons, flies and spinnerbaits, which you can attach artificial or real bait to, and attractants to make artificial lures smell lifelike.