honestly, i can see you having *alot* of trouble against anyone with a decent amount of armoured vehicles... all you have right now is the possessed's talons, 1 twin-linked autocannon and 2 twin-linked lascannons for 3000pts?! get some champs w/melta bombs at the vary least - power fist champs would be a much safer bet!
honestly, what are going to do if say you get assaulted by (or worse, *must* assault!) something like a wraithlord or dreadnought?! you're going to sit there and get squished!!!
drop your 'zerkers down to 8 for the free champ - you could even go with a big unit a 16 if you want numbers.
for the champs - if you don't give them power fists, then you should definately give the melta bombs! also don't forget the all-important talisman of burning blood for each squad...
i'd drop the bikers too - in a 'zerker army they're simply horribly expensive assault troops... (as you can't take any squad upgrade!) 4 is really all you need to daemon bomb your 'letters
i also recomend flesh hounds. honestly, whenever i play against 'zerkers, the hounds give me the most grief simply because of their speed! they may not have the same resiliance and power as the 'letters, but watching them go 18"+ in a single turn is truely terrifying for any opponent!
anyways, i hope this helps
cheers!