Does a linearly accelerated charge radiate? And if yes, is the electromagnetic waves emitted detectable from both its non-inertial frame and from other observing inertial frame? And If yes, doesn't this contradict with Einstein Equivalence principle?
Does [a] linearly accelerated charge radiate?
"It depends". Accelerating relative to whom?
Is the electromagnetic waves emitted detectable from both its non-inertial frame and from other observing inertial frame
Doesn't this contradict with Einstein Equivalence principle
This is indeed an apparent paradox in GR.
The solution to the paradox is to accept and acknowledge that radiation has no absolute meaning. Which is the reason of the "it depends" to the first question. The emission and detection of radiation depends both on the motion of the source (radiation field) and on that of the observer.
An inertial observer, stationary with respect to the accelerating charge, will indeed detect the radiation.
But a comoving observer, to whom the charge is at rest, will not detect any radiation. Simple reason being that yes, in their frame the charge is not accelerating. The mathematical reason is that, when you put this in Rindler coordinates, the charge and its field are enclosed in a horizon.