Coding Practices in the Industry

[LordMerlin]

I have a very paculiar question, and this is:
What are the normal coding practices in the industry, where I want to make money of my coding experience?
I offer web hosting, as well as web development, and I want to be able to offer turn-key solutions to anyone who needs it.
Recently I'v been looking at the whole HTML/TEXT-email thing, and I came to the conclution that using someone else's mime/html class works very well, in this case the one from PHPGuru. And this is where my question starts, and I hope this would cause some good descusion, as I'm sure a lot of people wonder about this.

Can I simply put together a product / solution, made up of my own code, and if needed an already developed class, and then sell it?

[weekender]

you might want to encypt your code, if you're going to sell that code to others

you can use zend encypter to encrypt the code and it should still work if you have zend server (i think).

i'm just doing freelance dynamic website design at the moment.