Yeah, I was gonna say the speed is the bigger problem. Even my biggest warships are designed to pull 2500-3000 km/s minimum. Active sensors are probably a bit strong, considering their range is almost double your max weapon range.
I'd ditch the gauss turrets for CIWS myself. You'll lose range and dual-purpose fire, but most missiles are going to cross the distance between 30k range (gauss turret range) and 1k range (CIWS range) in a couple of seconds, so you're probably only going to get one shot either way. And CIWS is a more optimized use of space.
Reactor core seems underpowered. Which is fine if plan to only fire a portion of your beams at a time (looks like you're planning 4 banks of 3 cannons each?), but I prefer to have enough to fire everything. Also, you're building one massive core. It's generally better, IMHO, to build a cluster of smaller cores (say 4 20-power cores), so that if one takes damage, you can continue to operate at decreased output.
For the same reason, I often build 1 or two more fire control systems than are operationally required, so that I have backups. But those are just differences in design philosophy.
I also tend to eschew the MIRV design (mostly because I haven't played around much with the booster/second-stage options) and just build a crapload of small, relatively short-range tubes (5-10km) and a handful of larger, slow-reloading tubes for long-range, large-warhead missiles. If I can, I get their reload times to be factors, so that for instance, for every six salvos of Strelas (the light SRMs), I fire one salvo of Molotoks (the big cruise missile jobbies).
EDIT: ahh, ok. If it's for a jump point monitor, then that's a different story. I'd up the power cores so you can fire all 12 particle cannons every reload cycle (120pwr, maybe in 4 30-point cores? that way if you have them grouped in 4 banks of 3 and you lose a single power core, you just turn off one FC and keep at it).
If it's an in-system monitor, you don't need that much fuel capacity. 100 days shoud be plenty, even with the shields. If you need to refuel, use a small tanker instead of wasting it by moving the whole ship off-station.