Had athletes foot. Now my body is feeling itchy, can foot fungus cause that?

Doubtful. Foot fungus uncommonly spreads to the rest of the body. One must consider other causes of your itching if persistent, especially if no rash is present.
Depends. Are you seeing a similar rash all over your body that you had on your feet? If so then the fungal infection is spreading and you need to get medication to help control the infection. If not then make sure you are using lotion on a daily basis since it may be just dry skin.