An interesting discovery:
In the posting No. 2 above, the fuller translation concerning the icon of St. Nicholas gifted to the church by Tsar Nicholas II states that the icon depicts St. Nicholas
with other Saints behind him, and that on that same column hangs an icon of St. Alexander Nevsky which has a small
relic of the Saint embedded in it.
Voila!
Here is a 360 degree view of the interior of the cathedral.
http://www.360pano.eu/show/?id=538If one begins by facing the iconostasis, and then rotates the picture to the right, one comes to the column mentioned above.
On the left side of the column is a large, full stature icon of St. Alexander Nevsky, and in the bottom left-hand corner of the icon is a small metal star containing the relic.
While on the right side of the column is an icon of St. Nicholas, with other Saints depicted behind him. No doubt that is the icon presented to the church by Tsar Nicholas II.
By the way, I believe that the Imperial family had attended the consecration of the church in 1900.
And they also visited it again in 1908 while in Revel / Tallinn to meet the King and Queen of Great Britain.
Well, enough detective work on this one question for now...