Any Electric train gurus ?

First off I dont know squat about electric trains. My grandfather used to always have a electric train set running around his Christmas tree. I loved it as I grew up watching it each Christmas. Well he as long since passed. I found the train set in my relatives storage. I have it now. I wanted to put it around my tree this year for Christmas. So I dug it all out. Seems the track is well... old. I found dates on the set which should be around 1972. I went to the local hobby shop and found out the set is the standard HO series. They had new track I could buy (the kind that has its own base so it can run on anything) I bought enough peices to make a oval around the tree, curves and two straights. I bought a new power supply as well.
I snapped all the track together and dug out one of the old engines and put it on the track.... nothing. I had to run the "throttle" to over half speed before it started to move. Then its slow. I put the throttle to max speed and it will move along ok.. but not near as fast as I think it should. Next... I only have two straights of track the rest are curved. When the engine hits the straights it sparks on the track and slows way down.. sometimes even stops.
I notice it leaves carbon on the track where it sparks. Does this need cleaned? I have checked all connections. The only thing I have been told is that the Engine is old school and prob thats the best it will do. I know my kids loved seeing the train go around. They loved the story behind it to. So if anyone can give me some pointers of what the heck I am doing that would be great. I also need to know about maintenace on the engines... can wd-40 be used ? I have one that is pretty gummed up from sitting. Another that is a steam engine chug chug type that doesnt like forward but loves reverse... I think a worm gear is stripped or worn. The main engine will go around.. it just fights the straights. Help ?

-RPM