What is the use of resistors or capacitors in a led strip?
If i connect the power supply in the middle of the strip, will it still work, or simply burn out?

Yes, it should work. This would be the equivalent to cutting the strip in half and powering one from the front and the other from the back.

This assumes that you are good at soldering, the connection point is fragile, you can easily pull the pads off. It is better to use the factory connections. 

Of course, the signal must attach to the appropriate end.