As for lead ships...
Wouldn't it stand to reason that, with the UFP only a year old, most members would still be using their own fleets? I mean, even 150 years from now, I find it hard to believe there could be an infrastructure so big, that it could build an entire fleet of newly designed ships in just a year. Personally, I always asumed that it took a few years, maybe even a decade or two, to phase out all of Earth, Vulcan, Andorian and Tellarite ships before Starfleet was made up of ships designed and build solely by Starfleet.