my husband is in the military so he is gone a lot, for months at a time and it does put a lot of stress and anxiety on my little girl. she is 3 now. his last deployment she was 2. I so get what you are saying, my daughter lashes out with the changes, gets more clingy, regresses in a lot of ways--she won't potty train I think in part because it is something she CAN control in her life right now. One thing that really has helped us out is to give her things that are just hers, like preschool, it's consistent and she gets to go away and come back. she also takes little weekends away to grandma's or to an aunts house which she really looks forward to because she gets to go and come back and I've found it helps her to process that even though daddy is gone he will be home. and when she goes she comes home. perhaps there is a preschool or dance class or something you could get her in for herself that gives her some time away from home.
there is so much in the environment that is confusing to a little kid, they love consistency and sometimes we are in situations where we can't give that to our kids, like with work schedules or my husband deploying. So I look for ways to create other structure for her. our bedtime routine is very structured, it gives her comfort. when daddy is here or gone it's the same. we made a little book up so that daddy and I were always on the same page and it also gives her some control because she can tell us what she will be doing next, but it is still exactly what we want her to do. I wouldn't worry about the stuttering, as others stated it could just be developmental. with my daughter she starts this whining voice where things are kind of high pitched, so I always tell her slow down, use your words--in your case when she is frustrated because her words aren't coming out the way she wants just gently remind her to slow down that it's okay. don't make the stuttering and issue so that she focuses on it. and if you are worried still talk to her pediatrician about it.
hang in there. its hard for me to watch my daughter missing her daddy and wanting to know the best things to help her. we just want the best for them--