You apparently had a 120v water heater, so the answer to #1 is yes. You now have a water heater that requires 240v, and as you have found it doesn't work too well. My advice is to run a 240v circuit. It's hard to say how difficult this would be, often when a water heater is in a basement and the breaker box is down there also, it's really quite simple. I'm surprised a plumber would not have recognized the problem when he did the installation. Perhaps you had a handyman instead of a plumber?