Empie NPC Killing is very simple now. If you know what you are doing.
You dont have to be 150km away from any sentry gun,
Only make sure that to Convoy is not from the same corps Station it is going too, and the only way this happens is if the are two Station owned by the same Corp in the system. only forgot about this and got a kestrel popped by the sentries.
I spent Most of saturday flitting between station in Isikano and Isanamo. In a Rocket Kestrel. I thin this is the purfest ship to do it in, it does constant damage is fairly fast and with and MWD can get to the Convoy quickly. Orbiting the convoy keeps the damage taken to a minimum, i fitted a Small shield booster, but never used it.
As for Loot Drops, Nothing really special. All NPC trade good, from Water and Garbage to Guidance Systems and Slaves. (ill post i picture of the loot when i get home tonight, if i remember).
You really need two characters to make it enjoyable, most drops are between 600 and 1200m^3 in size, i filled and Iteron V with 3 Nano & 2 Cargo Expanders in about an hour and 30mins.
To make money out of this you will either have to fly the loot where the best prices are or horde and set-up the sell orders and wait.
My only advice, well 4,
1. Find a system with a fair few Stations (6 to 7), From different Races,
2. Anything above a frigate is poissibly too Slow to make it worth the time as the Convoys Do warp into the Station @ 150 to 200km.
3. i did notice though after a few kills in Isikano that Pakkonan might reward with better loot, but alas there was no Convoys in there, So i Assume that System Status of 0.4 and below are void of Convoys. Due to unsafeness. LOL.
4. Aggro, when you do shoot and kill the convoys you will get the 15mins aggro from that Corp, so dont Warp to that Corps Station, wait till it runs out or miss that Station out on your patrols.
My only gripe is that no matter what the convoy ships are called they dont give any thing extra for youur trouble,
I thought that may be 1 in 100 ships might drop minerals or BPC or somthing good, but no luck
P.S. if you want to know how the NPC convoys set themselve up and move around the system etc etc etc, PM in game. either bigsteve or Scree.