This is a quick first pass- others will be able to offer better advice about competitive play, but I can offer a bit of advice.
First, your beast pack is not 10th ed legal (if that's an issue for your playgroup); in 10th ALL beast Packs MUST include 1 beastmaster, one clawed fiend, 2 khymerae and 3 razorwing flocks.
Characters attach to units again. You've got Wyches to attach to your succubus, and warriors to attach to your Archon, but you'll want wracks to attach to your haemonculus.
It's good that you have a Kabal Leader, a Cult Leader and a Coven leader- that will give you maximum pain tokens every turn if you keep them alive. You also have a strat that will let you empower all 3 of their units with a single pain token (instead of burning 1 token per unit).
Go to the Wahammer Community Website's download section. (
https://www.warhammer-community.com/warhammer-40000-downloads/).
Download the Core Rules to figure out how to play the game, download the Drukhari Index to see what your units can do and load out options for your troops, and download the Munitorum Field Manual to figure out how much those units cost.
Remember that a lot is likely to change when you get your 10th ed dex- at the very least, you'll get additional detachments, which may allow you to more effectively field different army compositions.
Right now, you only have one detachment, and it favours armies that include some cult, some coven and some kabal units. Your army is strong in the kabal department, adequate but sub-par in
th cult department, and inadequate in the coven department.
Of the 3 types of units, Cult units are currently weakest... so I wouldn't worry about beefing them up too much, but some coven support will go a long way with the current rules.