The whole laser dissipation thing really depends on what you want the laser to do. A laser that produces a tiny dot when fired from Earth to Mars could probably cut through a person instantly at ranges of a mile or more.
I'd say cutting lasers of the future would be short range, because at really large ranges (Sun to Mars, say) really tiny shocks (somebody walking by the turret) could put the beam off-target. I'm pretty sure that those laser-measuring tricks used an auto-lockon system with the mirror somehow signaling its position, which I doubt the enemy would be considerate enough to do.
Further caste ideas -
The master class might not be quite as strong as possible, enabling the military class to more easily handle coups and drunken aristocrat spoiled brats. Also, they might have advanced tissue regeneration and organ regrowth technology, enabling them to survive (If I get Sarg right, the master caste's main fear is of death, and thus cling to life as hard as they can).
The millitary/hero cast might have a partial hive mind rigged cyberneticly for their communications purposes, somewhat like an internet inside their heads. The "central server", or leader of the millitary/hero caste, might accompany the Emperor/President/whatever around to recieve their orders, as well as supply protection.
They might be a lot like Replicants, except their lifespans end when they age beyond peak functionality, which will be put off as long as possible via aging-slowing gene-altering. Also, some consideration should be put into if they have childhoods at all or not.
Further, they might have free will, but simply have an immense, all-overriding love of their masters (like dogs). This avoids situations, popular in speculative fiction, where the (usually evil) leader dies because his mindless army drones don't help without orders. Also, they might be as good looking as their masters, because they'd be what all sorts of people look up to (other, less pleasant reasons could be given).
The intel caste would most likely be nondescript and very adaptable, in order to appear in as large a variety of guises as possible. They might also have some sort of undetectable silent communications method. Further, they would have very little loyalty (there have been recorded instances of spies actually BECOMING whom they impersonated and opposing their masters). They would have as many wierd powers as the government could research, but as many of them as possible (most likely all) would be useless on the military.
The intel caste would be even more amoral (by our standards) than the masters.
I considered a "Courtesan" caste, but wondered if enough maturity was available on the boards for it. Something about "everything is for sale." put this in my head - maybe we could do an "actor" caste, which LOOKS like the master-caste, but has only ordinary powers. They're a sub-caste of the "average joe" caste. Just insert your own starlet joke here.
Also, I'm not sure the hard/dangerous labor caste is needed - couldn't robots do all that with much less expense and bother?
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And now for some ship ideas:
Since biological computers are now possible in theory, and it is also possible to make them as efficient as comparable metal/silicon ones, the mil-caste crew of warships might also serve as the ship's computer, in a sort of "Beowulf cluster" arrangement. A group mind refered to as the "ship mind" might be formed, coordinating the ship's activities.
Drones/Puppeteer - Basically, a puppeteer is a large ship that's devoted to storing and controling drones. The drones are armed with a small laser or two. Their purpose is to either fly over into the enemy fleet and blast sensor windows, stasis generators, and anything else small and vulnerable (think Luke vs Death Star) or to stay with their fleet and blast incoming drones. Drones are as small as possible, and are little more than ion engines strapped to guns. The puppeteer controls them - alternatively, the puppeteer might be all AI-run and break apart into drones.
Defense ships - These especially nasty bizaches string massive wires out in from of the fleet, and use large magnetic fields to deflect charged particle beams back at their sources.
That's all for now
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Seen on a Claymore anitpersonell mine: "Do not eat"