First off, your seller did not cheat you contrary to what someone here insinuates. It is a 16 year old car... when you buy a car like that, it should always be thoroughly checked before you put it on an hour drive.
Now, a "motor mount" is one of the rubbered, metal brackets that attach the engine to the chassis of the vehicle. And like the guy told you, they are usually not immediately "necessary". As for oil showing on your spark plugs, that is not a good thing; but it could be one simple thing: Your head cover gasket is failing or needs tightening. For your car, I think you'll need a 10 mm socket to tighten them. I had a 94 Mazda 626 and even a 1990 Accord that would do that. Remember, it's an older engine at this point.
Next time you add oil, I suggest you upgrade to a thicker viscosity oil (20/50)... that will help slowing leak if the leakage persisted. I would not advise you to take this car on other frequent 1 hr trips before you have it checked or at least fix the "known" issue you reported here.
Now, the worse case scenario for oil showing at your spark plugs (assuming you meant the inner parts of the plugs) is that your engine cylinders which after a number of years of rough driving relatively widened up allowing oil to be pushed up around the pistons -- in which case such a cylinder(s) would terribly misfire.
Your engine light is on for a reason. The computer is telling you something ain't right. Many a times, if there was a previous fault that was fixed, there computer will not recognize that the issue was fixed and will keep displaying the warning. To find out if it's a previously attended to warning: place your key in your ignition and turn it to ON position (do not start), then turn your head lights on... while your head lights are on, go ahead and disconnect the negative pole of your battery (or both) -- leave it disconnected for 10 minutes... Then reconnect it. Then go ahead and start your engine. If it was a previously fixed problem, the engine light should go away. If not, then of course, something is wrong!
Hope this helps... OK, I wish you good luck!