Don't put all your faith in Obliterators. They will die almost immediately to S8 AP2 or better weapons, relying only on that 5++ invulnerable save for being a Daemon. A Lascannon for instance, or a whole mess of other heavy weapons that aren't unusual in 1000pt games. They are good units, but just don't oversell yourself on their abilities.
So right off the bat, there's issues here and there. Your Lord has no Invul. This is a necessity for any Warlord model and needs to be fixed right away. You might even just take a Warpsmith since that is the more fluffy option and you're not really doing anything special with that Lord. There are pluses and minuses to either choice, so I'd go with what you want to do above all else. Then there's no place to put him. Are you going to walk a Lord up on some Obliterators? Why? If something gets close enough to charge Oblits, something went seriously wrong with your deployment and one Lord isn't going to help. If you want to put him in the Rhino, then you have too many people in a Rhino and need to come up with something new.
Your Marine squad has fallen to the same issue as many other starter squads. It has no role. You don't mix weapons on a unit like this if you don't have to. If you fire that Flamer, what good is a Lascannon? If you fire that Lascannon at a tank, are you actually expecting to be in range for the flamer and the Bolters to do something? Special weapons are meant to compliment one another, and CSM can even take two of the same. But honestly, this unit is going to be pretty useless either way, so don't invest in them. You'd be better off with Havocs and taking as many Special Weapons as you like, as long as you like four or less. The basic dude in Iron Warriors is not where Iron Warriors are strongest but Havocs make a great alternative that most other Legions don't or can't utilize as well.
I hate Helbrutes but the Helcult is the best way to use bad models in my opinion. I would try to swap that whole block out for Predators as soon as possible though. Two Preds with Autocannon and Lascannons would benefit from a Warpsmith nicely too.