Hey Subbiya
1> I would suggest you getting the 'Breakout Cables' They work good and are designed for the same application, in this case joining the LiPo to the ESC.
2> Yes you very well can. I myself was using Deans since the start of my hobby but seeing one deans burn during a flight, i have ALL my connectors to XT60 now
And yes XT60 can take around 60AMPs of current ( the original ) so no worries there.
3> Not really necessary, personally i initially flew with Kk and it was just resting on the center plate of my frame. I later used 2 layers of Masking tape for some damping but frankly didn't see any difference in the flight. Although yes you have the damping boards you can buy, which you can actually as they aren't very costly too. That is up to you
From your queries, i assume you are starting with quads and using a KK2 controller right ? Should you have any more problems gimme a holla
And contact me anywhere, FB, Mail no issues.