To answer the question about technology and politics during the 4000 years between KOTOR and Empire...no.
No real changes. Oh, for sure there were SOME changes. The fracturing of the Republic led to a much larger Fringe as former Republic worlds refused or failed to join the Empire and instead became independent. Technology advanced, but typically only as ongoing refinements of existing tech...not so much brand new ideas.
The reasons for this are myriad, ranging from the brutally honest (the KOTOR era was written up AFTER the Imperial period, and had to retain the widgets that made it "still Star Wars") to the dubiously logical (those 4000 years were turbulent times, with the Sith invading every few decades and nearly decimating the Republic in the process, resulting in a "one step forward, two steps back" sort of technological progression) to the boringly plausible (The Republic, for all it's democratic fairness, was a stagnant body, stifling advances...see also Traveller).
The general consensus seems to be that the overall tech level of the Imperial and post-Imperial age is actually LESS than that of the Republic at its height. This is borne out in the movies as well. Consider the last 1000 years of the Republic as a decline, perhaps...comparable to the Byzantine Empire of reality, or the fading Imperium of Traveller. A long, slow, Dark Age. That also makes Palpatine's takeover more plausible...
Mew.