Does QTP testing require in depth knowledge of VB script

You need to understand what you are trying to do with QTP. Generally, QTP testers work on three different levels -

1. User - Framework and automation test scripts are created by other people in this scenario. The user only executes the prewritten scripts and analyze the results. You will need little knowledge of vbscript in this case, just to be able to troubleshoot if something goes wrong. You should know following in VB Script - Focus on flow controls, creating methods, basic string operations, date operations, variables type, reading and writing to Excel, and commonly used VB script methods.

2. Script developer - In this case, you will need to prepare test scripts, adhering to the guidelines of the framework in your organization. You will need deeper understanding of VBScript and programming in general to play this role.

3. Framework designer/developer - This is a highly specialized role. You will need in depth knowledge of VBScript and at least another high level language, understanding of design patterns and good grasp of data structures and algorithms to play this role.

Think where you want to be in your career. In case you want to opt for #3, You should start learning VBScript.

You can visit W3Schools Online Web Tutorials and complete online tutorial on VB. 

Cucumber vs TestNG : Which is better?

I have been a long time user of TestNG.  Few months back, I started exploring about Cucumber. It was a wish from my client to create automation framework using Cucumber. I searched on web & found many blogs on Cucumber & its implementation. I started with assumption that Cucumber will replace TestNG. After working for few months, I came to following conclusion they are as follows -

Cucumber

TestNG

Cucumber is a collaboration tool, which lets non-technical people write executable specifications. Those executable specifications test your app from the outside - like a black box. Cucumber is not meant to be used as a unit testing tool.  It allows to write automated acceptance tests, functional requirements and software documentation into one format that would be understandable by non-technical people as well as testing tools You can implement your tests using the same language you use to discuss them with the business.  Cucumber adds the overhead of plain English (or other native language) to executable code conversion Good for acceptance testing

TestNG are unit testing tools. They are great for testing individual classes, but not great for executable specifications that are readable (and writeable) by non-technical people. It facilitates to test individual classes.  You can group tests using tags.  TestNG supports a lot of complicated practices like priorities, grouping, listener etc.   Useful when you have to automate large number of test case