Improving the Military AI

The AI is pretty good at many aspects of the game, except one: Military strategy.
To illustrate part of the problem let me summarize my latest game:

All intelligent AI -- gigantic map -- tight clusters -- PQ 10%, military 10%, social 10%, diplomacy 10% (I think)

The Yor managed to get at least twice as many planets as I do, they have three nice tightly clustered sectors of planets (almost like islands) while I have a long thread of sectors and another small clump off in the distance.
Early on (about frigate time), the Yor decide to go to war with me. We have been at war ever since, and we are up to avatar technology. They are more advanced than me, they have an ally who is as big as me, but I will win, I am almost certain.

You see they have been attacking basically the same place for years. The very tip of my empire, specifically the tip planet, has undergone a steady stream of enemy warships. At first I couldn't keep up with them, and they kept the first couple of planets in my chain clear, however for some reason they never sent any troops to occupy those planets, so I sent ship after ship wearing them down while I researched to dreadnaughts. At the beginning their frigates had double the hitpoints of mine and much greater attack values, but since they never capitalized on their success (with transports) the tide slowly turned in my favor.

Fast forward a few years, I have about 10 dreadnaughts parked at my tip planet, a fully upgraded starbase in the same sector with several dreadnaughts parked on it, and the Yor still send a steady stream of ships to be destroyed. Meanwhile, quietly I have been building up a massive assault force with which I can pretty much take the entire cluster of sectors nearest to me in just a few turns. None of their planets has more than a dreadnaught and a defender or battle axe guarding it, and I can simply sweep in with dozens of ships, including constructors, battle transports and dreadnaughts and rip their defenses to shreds. Once I take the system, I am sure they will send and endless stream of ships to attack whatever planet is closest at the moment. So I will fortify in the same manner and build up a strike force to take the next cluster and so forth. Of course I still have to deal with their allies and the other AI's, but strictly militarily speaking, there is zero chance of the Yor beating me despite their huge lead in production, population and possibly resources.

There are a few things I think the AI needs to do to improve its ability to wage war:

1) Strike deeper into enemy territory, target weakly defended critical planets. I realize this is heavy cpu time coding, but even adding a 25% chance to randomly attack any one of my planets would greatly increase the challenge of war, no cpu time needed.
2) Make the CPU realize when it isn't successful sending single ships and make it form up bigger assaults. Singly, all those dreadnaughts and rangers are no big deal, over time, my repair rate vastly outstrips their ability to do damage. If the Yor waited a couple turns and sent the same 50 ships at me at once, they could take down my defenses and it would take me a long time to build up enough ships to replace them.
3) Make the CPU more aggressive with transports, but make them protect the transports with combat ships.
4) Make the CPU target starbases with heavy military upgrades first, before attempting to assault a planet.
5) Make the CPU more actively use non-resource starbases as defense and production in its own sectors.
6) Make the CPU more likely to mass defensive units in the planets bordering people they are at war with.