One half of the tuneful duo, tuneful duo

The sentence is badly punctuated and awkward to parse. There should be a comma after "Vishal Shekhar".

A "duo" is two people working together. One half of a duo is one person. "tuneful" means that the duo are involved in music-related activities.

Thank you friend.
But still I cannot make out what this sentence exactly means. Do they mean Vishal Dadlani ogling at Katrina? or "Do they mean Vishal shekhar ogling at Katrina?

Also, please tell me what they mean by "what's better" in the next line

They mean Vishal Dadlani was ogling Katrina. The core of the sentence is: "Vishal Dadlani was ogling lustfully at Katrina Kaif". The phrase "one half of the tuneful duo Vishal Shekhar" gives further information about who Vishal Dadlani is.

"What's better" means that what follows (i.e. the fact that Farah Khan seemed a willing party) is in some way "better" than what has already been sai

Thanks a lot Wordy. Now I almost got it.
The only thing now I'm yet to make it clear is what they mean by "seemed willing party".

"seemed a willing party to it" means that he seemed to willingly participate in or condone the ogling. (I know nothing about these people or their relationships, so I don't understand the implication of this or why it is significant.)