Hi Guys,
I am sorry, what I stated for both questions above applies to my R7 and not my R4SP. However, if you use the self timer of the camera, the LEDs in the viewfinder will remain lit for around 8 sec. But, the LED viewed from the front of the camera will blink until about 2 seconds (then will remain constantly lit till the shutter fires) before the camera shutter is released. If you turn the camera timer off it will stop the shutter from releasing. So if you wish to use this to keep the viewfinder LEDs lit remember to shut off the self timer before the shutter is released.
As Lee has stated above, to lock the exposure (unless you are using the +/- overide which is in 1/3 stops) the camera must be set to spot A. As Lee has stated the shutter release has to be pushed to the 2nd pressure point. The reading will stay locked in and the confirmation will come from the spot A becoming extinguished. The camera will hold the reading for approximately 30 seconds but the stored values are extinguished as soon as your finger (or cable release) are removed from the shutter release.
Rich