I think you've gotten some great advice.
I would add, why not get her a baby doll (girl) for her when your baby is born. You can have your 'welcome home' party for your baby, but make it about your DD...what a great big sister she's going to be, and present her with the doll for HER to take care of. I would suggest a hard plastic doll that can be washed, get lotion and get preemie diapers for it. That way she can take care of HER baby girl and imitate you, while you take care of the baby boy.
Doing this went a LONG way in our house teaching our older DD to be "nice" to her baby and gave her something to do while I changed, nursed and rocked our baby. (My DD even lifted her shirt to nurse her baby too!)
At her age, the "art of distraction" goes a long way to refocus their energy. I think she'll be quite pleased with her baby brother very quickly after his arrival.
Also, make sure you have "big girl" arts and crafts, crayons, stickers or games for you to play with her while the baby sleeps. It's important to make sure she doesn't feel "replaced" by the baby or too jealous of all the attention he gets (afterall he needs more attention). I gave DD stuff to do during naptime that was special. It got put away after naptime because we "didn't want the baby to get into it". That kept these items "special" because she couldn't pull them out whenever she wanted.
Also, if Grandma and Grandpa can take her for a sleepover or dinner out (big girl activites) that will go a long way to making her feel special and give you a needed break.
Good luck and congrats!