Dont make it into a planishing hammer, or try to forge with it- unlike planishing hammers or power hammers, punch presses are not meant to hit things and bounce back- they break, and pieces fly thru the air. Not healthy.
Punch presses are designed for high production stamping and punching with dedicated dies. As mentioned the dies are the big money item.
You can buy some premade die sets that are blank- you add your own punch, or forming tooling- like this one from MSC-
*ITPD&PMITEM=03225083 This company also makes a lot of cool tooling that you could buy, if you have lots of money, or copy if you have a good machine shop-
It is not an ironworker, a shear or a press brake. It hits once, hard. Always the same hardness- so it isnt good for fussy bending. You could make a bending die, but it would need to be sized for the exact thickness of material you are bending, and the right angle. Same with shearing- it will shear, within its capacity, but its tricky to do freehand work on it without losing your free hand.
As far as books- there arent too many- but the best place to look is probably abebooks.com- thats the national database of used bookstores. A few books I have that cover the use of punch presses, but are pretty technical- If you can find it, the Bliss Power Press Handbook has some info. And Practical Design of Manufacturing Tools, by the American Society of Tool Engineers, Mcgraw Hill, has some info. But punch presses were never designed for the home user, so there isnt much in basic books- there are some technical books on die design, but use of the machines was usually taught on the job.