4512 is a complete set and includes everything you need to get him running - a good sized train, oval of track with a point, 9v motor and speed controller. The 4514 crane is an ideal companion to 4512- the cargo containers from both sets are interchangeable and can be used with either the train or the truck from 4514.
The Engine Shed is, in my opinion, one of the best train related sets Lego has ever made. Its expensive, but you do get lots of parts and the workshop is full of little details. Definitely worth the purchase.