This is a very open ended question. Like you mentioned the tools are very powerful and flexible so you should be able to build out most of the functionality that you would like. The problem is that you will need to first identify and create requirements for the functionality of the site. Asking if you can create something similar to another site is an easy enough question to ask but the answer would involve knowing and understanding the functionality that exists in these other sites. To tell you the truth I have not heard of some of these features and while it may be possible to recreate them with WebAssist tools it would need to be known precisely what the desired functionality is. This way we or the other members of the community can help you devise ways to accomplish this functionality, but without knowing what that is first it is very difficult to speak about how to do it.
I think the first thing you will need to do is go over these sites and try to define what portions of the functionality that you would like to include in your own site. In addition to this you would need to decide if you would like this to work differently in any way and what those requirements are.
