An excellent post, sums up most of my thoughts on the beta.
[Suggestion] With the starbase upgrade that doesn't allow the planet it is orbiting to be captured, make the planet totally immune to bombardment (add a planetary shield effect or such). The reason for this is that although you effectively force your enemy to attack your starbase to take the planet they can still destroy the population which is quite a big hit on your economy especially on smaller maps and if it is a terran or desert planet.
Also I've found an Advent players' defensive arsenal can take alot more beating with the various "shield-gifting" techs avaliable. Especially since gaining a shield also gives the structure shield mitigation it greatly increases the turrets survivability along with pretty much every other Advent orbital structure. A way to equalise this would be to give every factions' defensive structures their own shields, at least then they could compete with the Advent due to the great benefits of shield mitigation.
Another irritation of mine is that the shield mesh is barely visible without a mod. Perhaps increase the visibility of the shield mesh on weapon impact? Since its a rather neat effect its a damn shame you have to squint to see it most of the time.