What do you mean by design circuitry? If you are new using PSoC4 I would recommend you to buy an inexpensive Prototyping Kit like this one: http://www.cypress.com/documentation/development-kitsboards/psoc-4-cy8ckit-049-4xxx-prototyping-kits
Or a Development board with more hardware on it: http://www.cypress.com/documentation/development-kitsboards/cy8ckit-042-psoc-4-pioneer-kit
With these you can start working on your design without designing a board in the first place. Plus all the schematics are available, giving you examples of what's needed to use a PSoC4.
To program it you would use PSoC Creator available on Cypress website in the download section: http://www.cypress.com/products/psoc-creator-integrated-design-environment-ide
I have the PSoC4, cyc8-042 kit. What I was wondering, when I graduate and get ready to move on, and design my own circuit and I would like to incoporate a PSoC in my design, how do I field program it? How would I make updates or revisions? What other hardware do I need to look at?
The CY8CKIT-043 has got a snap-off programmer that you may use to program your devices using a 5 pin interface. Additionally there is the Miniprog3 that could be used as a more professional programmer.