No. The orginal Network Vision Panels are 800/1900. Band 41 requires a separate panel, called an 8T8R (8 transmitter, 8 receivers) panel/RRH's. And even though a site may have upgraded backhaul, it may only be sufficent for Band 25 or Band 25/26. Band 41 requires much more backhaul in order to be sufficiently supplied, so although a site may have 25/26, it may not be able to receive Band 41 yet.
And to your second question, no, they don't have to be cleared to use 800 before they can use 2500.
-Anthony