Queen of the Castle

Hey folks,   Well, some of you may remember me posting yesterday about a rescue dog that we were offered.  We went to see her last night. She's a beautiful, 2 year old, Cavalier King Charles Spaniel.  At first we were lead to believe that she was skittish/neurotic and very difficult (she's been through 2 homes in 6 months since her owner died), but when we met her she was great!  Calm and happy to meet us and very playful.  She and Juneau hit it off very well.  So, we took her home for a trial run.    She's taken to our home very easily and she really responds to us well. I hope so much that she continues to be happy with us!!  Now, she does have some pretty run-of-the mill behavioral issues that I hope someone can help me out with.  I want to start the positive, consistent training right away to try to wean her off her bad habits.  Here goes:

-she is VERY alpha with my other dog (Juneau—a 9 month old cavalier).  She takes her toys and chew sticks and growls/snaps at her when Juneau pisses her off (Juneau is young and playful and loves egging her on). She doesn't really attack her….she just growls a warning and snaps.  Her tail keeps wagging the whole time.  The breeder had her in his house with two other pups for several weeks and there were never any problems.  As such, I'm not worried that she'll hurt Juneau—it just seems somewhat unfair that she comes in and starts being all Queen of the Castle.  Also, Juneau kept jumping off the bed last night—almost like she was intimidated that Scout (new dog) was up there—even though Scout was just sleeping peacefully.  Should I try to correct this, or should I just let them work it out? Juneau doesn't seem stressed about it or anything—quite the opposite.  

-she barks at strangers, or at just about any noise.  Not, crazy, insane barking—but nervous, anxious barking—it also seems territorial to me.  I am amazed at how quickly she seems to have "claimed” us and how protective she is already.  How can we stop this?  When she barks do we distract her?  How?  We have been saying "hush” in a calm, confident, low voice and making eye contact. She does stop when we do this—but not constantly.  The higher the stress—the less we can control her.  Also, do we praise her when she stops?  Won't she think she's being praised for the barking?    Some miscellaneous things about Scout: she is very sweet and affectionate—when she's not bossing Juneau around, that is.  She is motivated by food, it seems.  Both of these traits might be things I can work with (withholding affection when she barks, giving treats when she behaves).

Thanks in advance for any help!