I am building a commander deck around Karador with an emphasis on enchantments with the new constillation mechanic. I have added creatures with bestow. Since Karador allows me to cast creature from my graveyard may I use bestow effects from there as well?
So they have to be cast as creatures?
The wording of his effect as a creature card signifies any effect of that card right?
Actually, Karador doesn't create an alternative cost; it just states something that's now true. You can pay any alternative costs for creatures you're casting with his ability, including Bestow or Evoke.
This is different from the example of giving Flashback to a card with Overload. Because Flashback is also an alternative cost, it doesn't work. However, if you're simply allowed to cast it from the grave ({Yawgmoth's Will} or Karador), any alternative costs are usable. Most notably, casting Yawgmoth's Will and then casting {Gush} from the grave by returning two Islands to your hand.
Edit - Added the word Simply for emphasis/clarity