I'm about 26 days into my account and I just want a bit of advice.  For background, I have two level 60 champions and I'm working on a third:

• Elhain lv60, bought masteries
• Dhukk the Pierced lv60, has up to tier 3 I think at the moment
• Pulled my first legendary (Septimus) and read that he could do the content I need for progression (Minotaur 15, Dragon 20, Spider 20(?), Lots of clanboss damage) and very importantly, he doesn't really need books, so I bought his masteries and I'm working on food for him

So a few questions:

• Would it be advisable to farm some gear from Dragon 13, or should I wait until I have more 60s and try for D20?
• My understanding is that I need to have a team that can bring a combination of damage, def/atk/spd buffs, healing, atk/def/weaken/spd/turn meter debuffing, cleanse, and revives...  I have Dhukk for def/atk down in one move on a 3-turn cooldown (as well as an unreliable taunt and accuracy down) so I 6*'d him because as far as I have read those are the two most important debuffs.  For the rest, it seems like it will be very difficult to check all the boxes without some crazy legendaries that can do these things.  I'm 4 days out from getting High Khatun, so she'll probably be my speed demon.  The question is, what are the most important things to have on a team if I'm unable to get ALL of it?
• My understanding is that putting together a clan boss team that can do Brutal or Nightmare should be my primary concern after getting my first 60.  Is it necessary to have a poisoner?  Do I need a healer if I have someone like Uugo who can put Leech on the boss?

Now, for the "who should I focus on" portion:

• Sustain support:  Uugo, Doompriest, Rector Drath, Tagoar, Hope (?), Gorgorab, Djamarasa
• Poisoner:  Anax, Kael, Outlaw Monk (booked up with dupes), Aothar
• Cleanse:  Doompriest, Heiress, Spirithost, Uugo
• Attack/Def buffs:  Giscard the Sigiled, Lightsworn, Doompriest
• Speed buffs:  Heiress, Tagoar, High Khatun soon
• Attack/Def/Weaken debuff:  Anax, Giscard the Sigiled, Lightsworn, Uugo

Then there's niche stuff like heal reduction and block buffs that I've only used very situationally so far:

Umbral Enchantress, Hellborn Sprite

I appreciate any input!  Thank you for reading.