The bite on your arm, was it deeply cut, or did your ig bite down and rock his head to do more damage? Or was it more of a less harmful warning bite?
He actually sounds pretty good for an abused, re-homed iguana. Be patient with his bite-threats and tail-whipping. It takes sometimes over a year to tame an adult iguana. His first check-up visit was mandatory and it's cost was average.
IMO your iguana is not sick, and probably very recently came from a home that it was tolerant of.
If he's not sick or skinny, he is able to go off his food for a month easily. Put out a good offering of chopped leafy greens once or twice per day. Soon he will start eating on his own again. Fruit is not an important part of iguana diets.
So keep your hands away if it has a chance of triggering a bite, and leave him quiet and alone for the next four weeks. Iguanas are happiest when alone with no stress going on. Picking up a reluctant iguana can be very stressful for it, and who knows for how long that big anxiety rush lasts. Ig your iguana stands perfectly still while you pet him, he might be doing the scared-stiff behavior, which is a reaction to the stress of being petted. If he takes food from your hand, offer different varieties, then let him figure out how to eat from a bowl. It's a serious trap when an ig is habituated to hand-feeding. They can never get enough food that way.