In our local library today, I came upon "War of the Aeronauts, A History of Ballooning in the Civil War," Charles M. Evans, Stackpole Books, 2002.
On pages 242/3 we find:
"Late in the evening of July 3  the Gazelle [the 'Silk Dress Balloon'] was inflated in Richmond and towed by train to a wharf on the James River and placed on board the CSS Teaser. Though Charles Cevor had attempted to correct the cronic leakage that limited the amount of time the Gazelle could remain aloft, Alexander [LCol. Edward Porter] was acutely aware that time was of the essence. With the balloon tethered to its deck, the Teaser steamed down the James River near to Malvern Hill.
"Just before sunrise on the morning of July 4, Alexander ascended, but his time in the air did not last very long.
"'After sunrise when the balloon began to get very weak, we emptied and folder her,' said Alexander.' The [Teaser's] captain, [Hunter] Davidson offered to run down a little further and land me where I could get out and probably make my way to Gen. Lee to report."
Shortly thereafter, Teaser ran aground, and later that afternoon captured by Union forces.
Alexander subsequently was able to seek out Gen. Lee and " . . . make my final baloon report."
From what I read, Alexander most likely was unable to gain much intelligence on this, his final flight, to report. I find no reference to use of the telegraphic service.
Perhaps greater intelligence would be found in "Fighting for the Confederacy-The Personal Recollections of General Edward Porter Alexander," Gary W. Gallagher, ed, UofNC Press, 1989.