Yay!
Keep in mind that the distances right now are mostly being measures in Astronomical Units. An Astronomical Unit isroughly the distance between the Earth and the Sun.
Light from the Sun takes only a bit more than 8 minutes to get there. Incidentally, it means that beam weapons in the SARP would take around the same time to cross over that distance.
Obviously enough, if you aren't a craft travelling at FTL but notice the attack coming, you can move out of the way. So, the trick in space combat is to close distance enough so that when you fire, the other will not be as able to react to the attack and dodge it. Even if the weapon's range lists it as 1 AU... that's actually only good at firing at something stationary.
Weapons like positron and particle cannons travel at almost 1c (close enough to consider it that way). The same goes for projected aether beams and the Miharu's main aether cannon in burst mode (which goes at the speed of light). The Miharu's torpedoes travel at 17 000c or so, making for nearly instantaneous hits at certain distances (which is why Nyton probably has a lot of problems watching their progress since they likely reach the travel as soon as he presses down the 'fire' button - even the slower AS-5 torpedoes, at 2500c, would get there pretty darn quickly). The aether cannon in continuous beam mode creates a 2 AU-long 10' diameter area which is flooded with aether... so, unless you can predict that sort of attack and avoid being in its area of effect... it's an instant hit.
Interdiction fields, in battle, serve a few purposes. One is to prevent a ship from escaping using its fold engines. Another is to limit the FTL capabilities of other systems, such as the Combined Field Systems (and thus preventing the hit-and-run attacks the Miharu has been making so far). Another is to keep ships traveling at Sublight speeds so that weaponry actually has a chance of hitting the target - if the ship travels at FTL, then weapons which travel at 1c are going to be hard pressed to hit.