What is the exact need of programming card.....?
Is it necessary to buy a programming card along with ESC....? I have searched this forum and found the procedure for programming ESC with Transmitter. So why do we need a programming card...?

Programming card provide a convenient way to view  the current setting on the ESC and set new setting more deterministically than 'Move Thy Stick' method using  the transmitter.

You might set the ESC using the Transmitter as there is no visual cue. Some time you may accidentally change the ESC setting due to accidental stick movement. Programming card would show you the the present setting.

I don't know, but its a good practice to check the ESC setting once in while.

Does these programming cards have universal compatibility and each ESC have separate kind of programming card...?

they are not universal... usually every manufacturer has a different programming card and will not work with other esc's unless and otherwise stated by the ESC manufacturer... if you are not using a esc in governor mode and in set rpm limits then i would ask you to save the money and not spend on a programming card and use yout tx stick movements to program..

If you are using most of the ESCs from hobby city then buy a turnigy programing card as it supports most of the ESCs sold by them. Also buy it only if you are programming many ESCs (atleast 4+ esc). Worth an investment if you plan to stay in the hobby for LOONG!

Do we need to program ESC each time when we fly or it is just one time requirement...?

Generally One time!

But some times ESCs memory gets wrong or gets reset for some reason (happened on plush for me). Then card can show the settings right away. As I said, its good to have one if staying in hobby for long and if you are using the same/compatible brand ESCs.

Can we find the current setting of an ESC without using a programming card?

If you are using align yes, it give a series of beebs and every beep has a meaning on how the esc is set up... am not sure about which esc you are talking about.. also I have used flyermate and this also gives a series of beeps stating the programming for the esc

I am going to buy programming card. Thanks a lot guys...!