1. Booshwa. The ExoTerra basking bulb is no better than a household A-type light we use all the time in our houses. Exo Terra is actually ripping beginner iguana keepers this way, by tricking them into buying what they don't need.
Get a regular store-bought exterior thermometer, and glue the bottom to a nice heavy (2 pounds) rock. Mine is mounted (not the bulb part directly) with hot melt glue, and I often check it to see if the thermostat and old-fashioned thermometer are in agreement.
For day heat, use the CHE plus a store-bought household type bulb with enough watts to keep him at the proper basking temperature in the cage. For night heat, get one or two of those black (not fluorescent) bulbs you can find in local stores. But you'll get frustrated at having to replace them when they stop working. Instead get a Ceramic Heat Emitter. They last longer than 14 years. Check out New York Herps or LLL Reptile. One of my 15 y.o. che's is still running faithfully. IMO don't bump them when they are hot.
I assume you are not ready to buy a thermostat yet. But they are the best of all for keeping the temperature within a degree or two of what you want.
Do all your heating at one end of the cage. Somewhere between the ends of the cage your ig will settle on his basking spot, or at least keep moving around to keep his core temperature where it needs to be. An iguana who doesn't move around at least a little during the day is probably sick or cold.
I guess I answered question 2.
3.) The MegaRay is a good bulb, but not for night. Iguanas need darkness at night. Here, the CHE is a good choice.
4.) I assume use these for daytime. Instead of the Zoo Med 5.0 get the 10.0. Again, the claim that the Zilla Day White Incandescent Bulb is no better than a common 100 watt household, A-Type bulb, and especially better than a walk outdoors when conditions are right.
Lastly, hang the UVB producing bulb down inside the cage., to about 8 inches at most from the top of your ig's back. If that seems too close then I ask you to reconcile yourself to these numbers. Hanging the UVB bulb higher might seem safer, but it may also cause your ig to get Metabolic Bone Disease later on, and it is irreversible.
Good Questions, with a couple of possible multiple answers.