The NX-Refit is a different ship renamed Enterprise and captained by Archer.
They're both different ships or "refits."
So it should be consistent in the commission dates, but for the NX, it just gets the NX original commission date. For the Constitution class Ent, the A has a different commission date than the original Constitution Class Enterprise.
Based on the "Draft" being near identical between the Galaxy Class (148.15m) and Odyssey Class (147.57m), i'd estimate it to have about the same amount of decks. 43 in total. Ofcourse, that number might be able to pushed slightly higher, depending on the deck heights, and space between decks.
However, taking the comment that "A couple of decks worth of height as the nacelles" that Tumerboy just said, I think we can peg the Odyssey around 41 decks rather than my low-ball estimate of 32 (which I got via counting an older image and the amount of decks on the Sovereign).
I know this may sound weird, but can we have the "Ship Specifications Pages" back along with the STO dev's specs of the Odyssey?
Also, on a similar vane, the "Vigilant class", how did someone work that out to be 32 meters tall, that's about three times the height of the Defiant Class?