You won't need too much hardware to set up Hadoop. The minimum setup is a single machine / virtual machine, and the recommended setup is three machines.
It is better to have some hands-on experience of writing and running basic programs in Java, as well as some experience of using developer tools such as Eclipse.
Some understanding of the standard software development life cycle would be a plus.
As this is a quick-start guide, it does not provide complete coverage of all topics. Therefore, you will find links provided throughout the book o take you to the deep-dive of the given topic.