16-17mpg from a carbureted Honda is pretty bad. I'd say you're definitely in need of a fresh carb, and likely some other tuning work. A fuel injection system on that car is more work than the car is worth.

The oil leak may be coming from your oil pressure sensor. That's located right next to the oil filter. It may also be a leaking PCV system, that's located just above the oil filter. Get some of that blacklight responsive dye that shops ues. Put it in your oil, drive for about 100 miles, and then use a blacklight to find where the leak is coming from.