You're welcome. Another option if you want both of them to be outside is to have one of your hens in a chicken tractor. They are actually pretty easy to make (especially since only one would need to be in it) and you can move the tractor around the yard. Hope I helped ;).
Do not worry too much about the broodiness. They do not stay broody forever, so just give her some time. Another good thing to do is put her in a chicken tractor with food and water, but no nesting boxes. If your hen is more independent, than I would say to leave her by herself but if she is not...
Maybe keep them separated for a while until they calm themselves down a bit. One is also probably broody but don't worry if one is because the hen will eventually stop the broodiness.
Do you have a fence gate? If so, than make sure there is a lock on the fence so there is no possible way your chicken could open it and get out. Also, it's possible your fencing is too low. If THAT'S the case, then I would recommend making a run for your chickens, or make a chicken tractor...
Your Buff being aggressive is totally normal. All chickens have a different personality, and your Buff is probably either going through a stage or maybe she is getting broody. Buff Orpingtons do get broody sometimes, so don't worry, I am sure your Buff will be sweet as ever if you just give her...
Oh, and in case I kind of just got you a little worried, let me tell you, most chickens with Marek's disease DO live, but it is still very important to take your chicken to the vet, in case this is a bad case of Marek's.