On the subject of design leaking... If you do design leaks, you should obfuscate them somewhat. Keep in mind that the Russians for instance still have designs from World War 2 as being classified information, and most military designs today remain in use for longer than ten years (See: F-14, F-15, F-16, F/A-18...) so that would be a really short period of time. Now, yes, we should be seeing rapid technological changes as we go along, which means things might be obsoleted earlier... but if we've got it as like. After they've been encountered, on the Solarian System Network (since I assume we've got some sort of internet equiv for communications) we could have people posting their theories on what each ship has. Sometimes they're pretty close, other times they're going full 'Communist Propaganda' with the performance specs.