Doron,StrataFrame can definitely help you and handle all of the areas that you mentioned on a website like this. I think that first you need to make sure that your expectations of what the framework will do versus what is developer application design need to be established.
We have developers creating extremely complex and vast applications using StrataFrame...both Win and Web forms. But you need to understand that StrataFrame is a framework...not an application generator. There is a difference and many times people get confused as to what a framework will do for you. Let's just start with your questions:
Is that possible to use the Role Based Security for this development? When the user logs in I will to validate his/her account as for starters.
Yes. There are even some user contributed samples that show a bit of this. However, there is more work when doing this online as we do not provide a UI for the web side. The reason that we don't is because there are just too many opinions as to what it should look like, function like, etc. But you can programmatically create users as you need them. So you can create a page that captures the users information then create a RBS user record. All of the authentication methods, etc. are in shared (static) classes so that you can access them from anywhere.
I need to enable the user to create an account and after the credit card was validated, then save that record. In the above particular page the account is good for 30 days!! How the SF will handle that?
Again, this goes back to application design. Is this really the responsibility of the framework or your application? However, one idea would be to use RBS and have the account timeout after 30 days. That way they would have to either pay up or go through some type of activation cycle to regain access to a page account.
Also I need to perform a Search for people in several data bases while each one could be a 100 to 200 GB. Obviously it will be partitioned and then display the data for the user. Is there something in SF that can be utilized for this kind of Search?
StrataFrame comes with many different tools to give you access to your data. In regards to size, we have users with databases far larger than this. But like anything else, a good database design is required to achieve the optimum performance. As such, we have a need for something similar in our medical application. When we need search across multiple databases, we may create a sproc or view that allows us to pull from a number of different databases. You can take many different approaches here, including doing it all through a BO talking to different data connections (StrataFrame allows you to connect to as many different databases, servers, etc. within the same application).
In short I need to know if your Framework can help me in anyway for this type of web site development?
Absolutely. But you need to understand that a framework is not an application generator. When it comes to managing data, business logic, security (if you use RBS), managing BO sessions, etc. it will make a vast difference in time and performance. But if you are expecting it to generate pages and code for you, it won't.