Also I was interdicted by an NPC Eagle pirate twice yesterday while flying my Anaconda. Stupid pirates...
1) Don't colour your text. It makes your posts impossible to read for many people. I have stripped the colour tags for the purposes of this reply.
2) You're right, there's no rhyme or reason to it. My A-fit Vulture got interdicted by unshielded Sidewinders twice yesterday. A single solid shot is more or less all it takes to wipe one out with large bursts. It seems like a waste of time