How long does it take to write something like bambooinvoice?

[eluser]adityamenon[/eluser]
How fast? Rather unanswerable. It depends totally on your way and pace of working and learning.

Should you be "thorough" with PHP? I've been coding since the past 4 yrs, built quite a few big sites, but I still don't have clue about how the bcpowmod() function works. I will only look at it if I need it. You can never be 100% knowledgeable about PHP. What you MUST be thorough about, however, is every bit of the syntax and all the language constructs available.

Knowing OOP best practices, standards, and design patterns will help you big time in handling giant projects.