One can assume that the Romulans would be going as fast as they could given the circumstances, but this is not as clear-cut as it may seem. Starfleet ships are generally given three speeds - normal cruise, maximum cruise and maximum rated. According to the TNG TM normal cruise is the speed the ship can hold until fuel exhaustion. Maximum cruise is the fastest speed it can sustain for a long but unspecified period of time. Maximum rated is the ships top speed, beyond which you risk immediate engine damage - the Galaxy class can hold its maximum rated speed of Warp 9.6 for twelve hours according to the TNG TM.

Since we don't know how long a trip the Romulans had to make, this only tells us that Warp 9.9 is somewhere between the maximum cruise and maximum rated speed. However, since we know Voyagers maximum sustainable cruise speed is Warp 9.975 ("Caretaker", "Relativity"), then the Prometheus would have to be faster than this to be rated as the fastest ship in the fleet. Hence, I've put Warp 9.9 as the top cruise speed and stated that the ships top speed is expected to be Warp 9.99+.

The Prometheus was able to inflict damage on a Nebula class ship after just a few phaser strikes (some said the Nebula was destroyed, but this is not made clear in the episode). This led me to make the Prometheus' phasers Type 12, very heavy for such a small ship. From her looks, the Prometheus seems to be a cross between the intrepid and the Sovereign. She has Sov-style nacelles, but the basic hull is clearly an Intrepid variant. Her combat power indicates that she is built like the Defiant - no laboratories, no holodecks, etc. to give extra space to support the type 12's.

Of course the multi-vector attack mode is something new, but I don't really know how this would help the Prometheus. I've suggested that she was originally supposed to be a fully warp capable development of the Galaxy class saucer-stardrive concept, with one section carrying the labs, families, etc. away while the other went into battle. Then Starfleet changed it to a warship and added lots of weapons in the 'civilian' section. This is just a guess on my part of course, and the episode does not make any of it clear. One other guess is that the docked mode is intended to hide the strength of the Prometheus - when docked one third of the ships arrays and 60% of the torpedo tubes are hidden from view. The Prometheus could be seen as an attempt by Starfleet to field much more powerful ships while still trying to maintain a non-military face. I don't like this idea, however, as it implies a certain dishonesty on Starfleets part.

With the Galaxy class I gave strength numbers for the ship only in docked mode, but since the separation aspect is apparently a very important part of the Prometheus concept, I have detailed the weaponry of each section, the total for the separated sections, and the total for the integrated ship. The number of arrays and torpedo tubes carried is taken from a newsgroup posting made by Ryan McReynolds. Ryan says he got these numbers from analysing the pictures of the Prometheus in Star Trek : The Magazine. Since those pictures are made from the CGI model of the ship actually used in the episode, they should be regarded as being pretty solid.

The sizes of the Prometheus are reported to have been given by Rick Sternbach.