The requirements for project management depend very much on what level you are involved. For developing applications as a project manager the minimum you should take care of:
1. Document outlining application spec and functionality
2. MS Visio: Application Workflow Diagram
3. MS Visio: UML class diagram
4. Review 1.-3. and see if all describe the same workflow and functionality
5. Programming the API
6. Review 5. to see if it actually fulfills what 1.-3. set out to do
7. Program code
8. Create documentation with phpdocumentor
9. Refine API & code where necessary
10. Test, test, test (if you have can, unit-test)
11. Test some more
12. Test a little bit more with other people involved as well
13. Praise everyone you've worked with and get them to buy you beers.
14. Run some tests just to make sure.
That's just a very, very, brief outline: the most important things to me are
1. clarity at all levels and for everyone involved
2. clear structures
3. KISS: keep it simple, stupid.
4. Always think about your application as if you were looking back at it from 2 years on.
Just another thing: have a look if a similar project exists somewhere - if so: great, you can probably learn something.
For some background reading:
http://www.sitepoint.com/article/develo ... -success/2
http://www.sitepoint.com/article/proces ... umentation