The first thing to look for is whether it has upgraded memory -- are there two cards or only one under the battery cover? One of the ram expansion cards is probably worth $50-75, so take a peek.
Then you'll need a power supply, which it is wise to get right as the machine is easily fried. The manual will be useful to read, too, as the OS is very distinctive, and Raskinesque in its task-orientation.
There is not much on 68kmla on the Newton that is terribly worth pursuing, truth be told, though I and a few others make an effort. The best fodder is on the wider web, which you'll find easily enough. As a starting place, however, unna.org is the best place to go for software (not all of which you can use without unobtanium registration codes, by the way, but some of it you can); you'll find that the eMate manual is there, too, along with an image of the CD that came with the machine, etc. etc.
It is possible to network the thing to an OSX box, but as we generally have no shortage of old machines, I recommend the original Newton Connection Utilities when the time comes, along with Word 6 or later, or ClarisWorks, for uploading NewtonWorks documents (you'll be surprised how well even sketches are preserved), and Claris Organizer 2 for the Calendar, Names, etc. It all works seamlessly.