Regarding your Points, Please find my comments
1. how can we achieve parameterization or data driven from an external file.
Here is the article from which you can see,
You can also download the samples from here
2. Can we perform descriptive programming using test studio. for example i have dynamic objects that are populated on the application then
can i write a driver and store all these elements in a seperate file such as excel and then basing on the requirement can i pass this elemnet as an arguement and perform the operation. If Yes please provide the process as my application has lots of dynamic objects
When you add Elements into your Project using Test Studio built in Feature, Add Elements to Project, Test Studio automatically capture the Properties of an Element and Stored in readonly file Pages.g.cs or Pages.g.vb, depends upon the which language you are using for Project(C# or VB), for dynamic elements you can use Advanced Find Logic as mentioned in this article
3.How can i write my own code instead of recording.
This is simple, just create a New Test (NewTest1.tstest) and Add Code behind file and start Coding
4.Where can i find all the methods with which i can write my own code.(An exampke with code would be helpful)
Same as 3
5.How can i create reusable functions and call them in my script.All these are application specific reusables such as login.
you can use Modularity Driven approach, Create Common Methods for Lo-gin, Log-out and use them in Test wherever its required
Here is the Example
//Maximize the Browser
//Launch the URL
//Wait for UserName Textbox Exists in DOM
Pages.app.Username.Text = username;
//Wait for Password Textbox Exists in DOM
Pages.app.Username.Text = password;
//Wait for Login Button Exists in DOM
//Click on Login Button
Access this in Coded Step
public void LoginintoYahoo()
//Create object for Login class
Login objlogin = new Login();
//Call the Method to Login into Application
6.How can pass the test data to my variables within a script.
Same as 5
Please let me know if any other info required