help me sort this out

3. Lastly, I saw somehting about making alterations to trains (wheels and power) to make them faster and stronger. I just wanted to get some thoughts on that in general. Is it overkill? is it fun? easy? etc.

Apart from changing out the motor for one that runs at a higher RPM, the other thing you can do is to run the regular motor at a higher voltage. It's particularly easy to adapt a 'C'-size battery compartment to hold either two 'AA' or three 'AAA' size batteries using an ultra-cheap battery box to hold them in. A small amount of grinding away of the housing using a Dremel-type tool and a suitable bit is all that's needed to make it fit. You'll find links to videos showing this procedure if you search around a bit. Here's one.

Or you can do both. Correct me if I'm wrong but I think Ucwepn's Spencer that he refers to above has both an uprated motor and 3v of juice?