Welcome. At this age I suggest you not get involved in discipline beyond advising your husband in private his overall strategy.

If she fails to sort the laundry let him deal with it. But if she is trying to start a fire on the living room floor you need to deal with it but otherwise let her make her own way among the rules he has set down. I'd also try and not be the tattle tale especially if its something he'll discover on his own anyway.

If she's supposed to do her homework as soon as she gets home and doesn't leave it alone. It'll catch up to her soon enough but if he asks you don't lie.

Make it clear you're not there to replace her mother if she seems to have problems accepting your role.

Most step-mothers come here after a war has started between them and the kid(s). Should it look like things are moving in that direction you'll want to be aware of this concept: http://www.steptogether.org/disengaging.html

When you have the talk with DH, be sure you are listening to what he is saying and not what you want to hear. I have made this mistake. Make sure he is clear and so are you. Before you start disciplining, do a lot of fun stuff with her so it will be easier to take the negative feedback when you give it. If he isn't going to set firm expectations for his DD and support you in your efforts as well...you are SOL my friend. Because you are emotionally involved, maybe giving him an article about what happens to kids that don't have consistent discipline end up?

You don't. It will be your single biggest mistake..... If issues come up it's best to go to DH. Express your concerns and let him deal with it (which he won't). If you are already wanting to lay the hammer down you are in for a long long long haul.......

Just don't. Let her father handle all that or she'll see you as the bad guy (if she doesn't already) and will make your life Hell (if she doesn't already!!!)