Post a picture of the terrarium, that will help with deciding what light fixtures are necessary.
Water dragons need UV light, high temperature basking spot, branches for climbing/basking, a moderate temperature enclosure, and a large water bowl.
UV light can be achieved either by fluorescent or incandescent bulbs, however fluorescent is by far the better choice. Incandescent bulbs that are designed for UV light production only last a couple months (the bulb doesn't burn out, but it no longer produces the appropriate wavelength of light and must be replaced), whereas fluorescent bulbs designed to produce UV light can last a year (like incandescents, they don't burn out but their UV-light producing days run out and must be replaced).
The overall temperature of the cage should be maintained at ~80 degrees with incandescent bulb(s). HEAT ROCKS DO NOT HEAT CAGES!! Do not use a heat rock.
The basking area should be made by having a focused heat source (ceramic heaters work very well) with a branch/elevated perch underneath it to allow the water dragon to get closer to the heat source. This should be turned off at night to allow the temperature of the cage to drop somewhat. The temperature in the basking area should exceed 90 degrees.
A large water bowl is necessary to allow the water dragon to climb completely into it. Expect to have to change the water in this frequently as it will get dirty, and crickets will jump in it and drown. Placing a rock against one edge of the bowl will allow some crickets to crawl out of the water if they happen to jump in. A 12" diameter, 4-5" deep ceramic bowl should work well.
As for thermometers, any of the ones at a pet store will work well. Doesn't have to be fancy. I usually use one that sticks to the front glass.
For climbing sticks, make sure the branches are thick enough to support the weight of the water dragon and that they are solidly mounted to prevent them from falling once the dragon climbs on them. If you use branches from outside, NEVER immediately place them into the animal's enclosure - you will be bringing in mites, etc. Soak the branches in water so they are completely saturated, then bake them at ~300 degrees in the oven until they are dry. This should adequately kill anything that might be living on/in the branches to make it safe to use.