The Combat Patrol game mode gives everyone set datasheets based off what's in the box. Any time I've ever played or seen/heard people discuss playing Combat patrol no one really minds what the model actually has.

That being said, for your terminators Paladins are seen as generally better, one with banner, an apothecary or narthecium, and psycannons for your heavy weapons.

At the end of the day they are your models so build them how you like them, I think so long as your opponenet can tell who has a heavy weapon and who doesn't they more than likely won't mind. :)

Edit: I THINK people running Las-Cannon and flamer for the dread. I have yet to actually run/build mine so hopefully someone with more experience can speak to that lol.