I have a very old set and am in need of parts for the engine.  I believe it was a #90020 set. 

Are parts still available for this engine?

Are there any parts drawings avalable to facilitate identification of which parts are needed?

I have a new Bachmann (#81099, undecoratd) 4-6-0 Anniversary Edition locomotive with tender and chuff sound built in. I would like to convert it to be able to run from battery power with an AirWire.  The batteries would be in a box car, so that the setup can be used with different engines.

Has anyone done this?  I would appreciate any clues as to the wiring changes needed to make this work.