I know you said this is 'Noncompetitive' so I will only pick on the really 'poor' parts of the list! (Not that their is a huge amount, it looks a fun list)
I will look into changing out those other things you pointed out and will be dropping the marks on the cultists. I have one thing tho...
"Drop the Havoc, you cannot use it at the same time as the battle cannon. Same goes with the Lascannon although you can snap fire it, it still needs 6's so may as well get a autocannon that will allow you to shoot twice."
-From what I have read in the big rule book walkers and ordnance weapons work fine together. I have heard this before tho. This is my understanding of it with page numbers from the book to back me up.
Ordnance Weapons: "if a non-vehicle model fires an Ordnance weapon, ...the model cannot fire other weapons that phase." 51pg.
Walkers: (listed under the vehicles section) "A Walker that moved can still fire all of its weapons in the subsequent Shooting phase" 84pg.
With these two rules it seems like to me the Defiler can fire all it's weapons even the battle canon. Unless this has been FaQed and I missed it. I'm not trying to be rude or a rule book thumper either, it's just how I see the rules read in conjunction.