It is sad there are so few feature-length space war films. There are no Battle of Jutland ironclad slugfests, and no age-of-sail ship-of-the-line slugfests other than ROTJ or ROTS. Starship troopers has decent projection of alien planetary defense layers. BSG03 had useful depictions of space/surface combat. Independence Day was a decent synthesis of the genre. It cannot really inform your question. You can check Wrath of Khan for some classic age-of-sail cat and mouse combat. Undiscovered Country as well. Aliens and Predator offer ground force insight.
One thing I think it is critical to have clearly in mind is what is the resource value of the objective, in terms of what the technology can do with or without. Are planets absolutely critical? What fuels and materials are needed and are they found solely on planets? When you start postulating combat in a Kardashev III you need to be aware that they may be as tied to planets as modern civilization is tied to port cities. (We used to be; we no longer are.)
Like the Guns of Navarone, the primacy of Hoth surface defenses vis-a-vis orbital offense rings true. A planet can simply support guns more massive than what can easily be lugged in. But then on the surface, beneath the ion cannon, minute-oriented mobility generally trumps macro-oriented stability. Useful: Maginot Line.
SW EU has a useful craft called the interdictor which forces ships out of hyperspace. I assume there'd be silver bullets that can punch through such interdiction while ordinary military craft would be halted. It rings true to life that there is always an arms race between predator and prey, between offensive weapon and defense.
The ISD serves generally as both aircraft carrier and battleship - there's got to be some delicate balance between the two roles, and there's got to be capital ships specialized to roles.
There could also be forms of cyber warfare on a galactic scale.
Useful to know: Sun Tzu and great battles like Thermopylae, Salamis, Syracuse, Cannae, Carthage, Tyre, Actium, Hastings, Agincourt, etcetc.
Useful books: EON, Ender's Game, Gateway.