Still a guide inside Muggi's main guide. Thought there was a guide solely for pures, but I guess not. http://forum.tip.it/viewtopic.php?t=565504 Ctrl+F then type in The Pure Method
Smokey well??? Thats a death wish if your using full set!! you need a facemask It's actually possible, the smoke can't take away your last hitpoint, so with protect melee on, the only way you can die is by attacking a dusty or getting an evil chicken.
I've helped somebody to finish their task before when they ran out of prayer pots, so the killcount definitely works. If you're sure they're linked it should work.
I'd say wait until you're higher level. At least 100, training slayer. For now just stick with food and if you want to, get bones to peaches. Gives you a full invent of food for the price of 2 nats. Very good for bloodvelds/ankous/dust devils/infernal mages. Really worth getting.
~Do i need the majority of the damage, or only the last hit to get the Slayer Experience?~ You'd have to test it out, the last hit definitely gets the killcount, can't remember about the xp.