You seem to be in the right place judging by some of your questions, it's just some of your thoughts need a little more thinking, consider reading http://www.catb.org/~esr/faqs/smart-questions.html to get an idea of how to scope your questions.
Most SE sites tend to steer away from open ended questions asking for best/opinion/ideas.
There are also many questions that answer your questions, it's just a matter of searching using Stack Overflow or Google (
So you want to know how to build a site like X?
Start reading about the technologies behind it.
E.g. Stack Overflow Which tools and technologies are used to build the Stack Exchange Network?
From there you chunk down into the various languages and tools and so on
To be more specific, say this question
This question needs to be broken into two questions, one for e-commerce and one for gaming. Then chunk down again to a specific language. The chunk down again to your doubts behind the security of X feature in Y language, and then chunk down again until you have developed a near perfectly scoped question for us to read, vote up and answer.