Each fuse or circuit breaker is a circuit, with one possible exception on 220vac circuits. A 220vac circuit needs two fuses, but they should be tied together in some manner. You may not have any. An electric dryer, stove, WH, and possibly other things are likely 220vac. Those are probably now on circuit breakers, but could be on a double fuse assembly. In the USA, in a residential setting, your power coming in is actually 220vac, but the neutral is half-way across the transformer that feeds the house. So, from neutral to one hot is 1/2 the voltage or 110. If you need the full voltage, you use the hots from each side of the transformer, which gives you the full 220vac. If you mess up and get two hots from the same side of the transformer, you'll have zero volts, but it's still 110vac if you measure it to ground. Ground normally should not have any current on it.
Yes, you can install a grounded recepticle IF you mark it as GFCI protected, no ground. Note, some things really want a ground. They usually include the stickers in the box. If you use a standard circuit breaker and install a gfci outlet in the first box of the string, feed the downstream outlets from the load side of the GFCI, then it will do the same thing, and may be easier to reset if you trip one - you'd do it in the house rather than having to go back to the panel. But, knowing WHERE the GFCI tripped could be a pain. It's easier if they're all in one place. A GFCI recepticle is less expensive than a breaker.