I'm not sure how this compares to the Edgeville ring, but using the Ardougne monastery teleport and then running east gets you to a fairy ring fairly quickly.
Do Royal Trouble ASAP then put at least 750k in the coffers. Failing that, just put in as much cash as you possibly can. You're really missing out by not doing that.
My arms patch actually is a disease free patch I think, it has never really taken longer than the other patches for me. But yeah use compost. My Arm's patch does get diseased; he just cures it for you.
The boosted stats are just for the tormented demons, though. You still have to worry about the balance elemental, so bring good gear and work on prayer switching. Also, you can boost for the required herblore level with a greenman's ale.
The seers' headband is an inextinguishable light source and works whether you wield it or not. For poison and disease you could try sanfew serums since they cure both at once and also act as a super restore.
What I did was enter the city with a greegree equipped and go to the archer monkeys by the agility course. I was able to kill one of them without getting caught.
Itchlarin's little helper and Dealing with scarbas are the quests you are talking about, i believe. Enakhra's Lament and Dealing with Scabaras, respectively.
As a side question, is it possible for promethium spears to drop from forgotten warriors? I don't think I've yet to see any forgotten warrior wield any type of spear yet. The only spear drops I've seen were from hobgoblins.
I just focus on one healer at a time. For me, Jad wasn't even close to full health when I killed the last healer, but that may have been due to my deflect curses.
It depends on how slow. The trick is learning the animations for each attack and using f1 and f3 to switch between inventory and prayers. I was about 82-83 range I think.
I did not go to a safespot. I used long range when killing the healers to make sure I didn't get too close to Jad and rapid otherwise. I always prayed magic unless I saw him preparing his range attack, so if I saw he was about to use magic, I quickly targeted one of the healers and focused my attention back to Jad. I listened for the death sound to tell me when each healer died.
Definitely use eagle eye. I found it easier to simply kill the healers and then finish Jad off once they were all gone. This way I didn't have to take my attention off Jad very long.
You have to have (or boost to) 79 slayer to kill wyverns. It's aquanites that need 78 slayer. Wyverns are 72. You can use summer pies to boost your slayer I believe. Wild pies boost slayer by 5.