Elizabeth,
Riding around on a dry motor would have made a terrible clatter, and most likely ruined the motor- as in seized it up. I think your okay. I'm the cool headed type that gets all the info before I rip someones head off (want to make sure I get the right head, ya see). So I still propose you stay calm and optimistic that it may have been/ still is something else. You may very well have a flaky switch or something else, but what you describe does not sound catastrophic. Let the dealer have it for a day or two to check it out and double check all the electrical connections (and get a loaner while he has it in the shop).
He (the mechanic) is partly correct about the oil getting sucked up- it's just not the filter that does it. The oil travels through the motor. So after it is ridden, if it is shut off the sight will likely be empty, or at least low. As the bike sits, it seems to "fill" up as the oil drains back into the crank case.
One more thing- from what you have posted, it seems you are overfull with oil now- which is also bad. You need to get the excess oil out. If you have access to a small fluid pump: level the bike with what ever you can (lift, wood, whatever) and suck the oil out of the fill hole until it is 2/3 up the sight glass. Make sure the bike has been sitting for a while.
P.S. I'm curious. When the bike was not starting, was it clicking or making any noise?
