maybe this will help you some.
Print is used to check and be positive something is written out. It returns true (1) if it worked, false (0) if it didn't.
Echo on the other hand, just puts the text out.
Printf means Print Formatted, and it's a directly the same as the one in the C language. There are tonnes of tutorials on how to make printf work the best for you, just look around.
The ones you left out are Sprint and Sprintf. Sprint is "Special Print", where it uses a special syntax to better format a string (even better than printf). Sprintf is Special Print Formatted, and again, it allows even better format control over the text. If you want more information on any of these, go check out a C handbook or manual (the php manual kinda accepts that everyone knows this because they are coverts from C, but hopefully that will change soon).
And twiglemac is right, PHP is a dynamically typed language. That means that you don't have to worry about the difference between a Number and a Character array (a.k.a. String). Type casting is the same as in java, but one of the best features of PHP is called type juggling. it allows character arrays and numbers to be used practically interchangably. I have a tutorial on this over at evil walrus (a great site for php snipits),
http://www.evilwalrus.com/viewcode.php?codeEx=689 , it allows you to see the lenght of which PHP cares about numbers and character arrays. Hope this helps.
cirox out