The previous poster already gave some great advice, but I'd like to add some towards the emotional preparedness for your 2.5 year old. Even if your child may not *seem* to understand abstract concepts like moving, you can break it down in a very simplistic matter-of-fact way. For example, we moved from Eastern Europe to VA earlier this year when our oldest was almost 3 and our youngest was 18 months. We told our oldest that the movers were going to come and put all of our things in big boxes and then put them on a big truck (which they got to see). For our situation, we then told her that the truck was going to drive and put our boxes on a big boat and then the boat would bring our boxes to our new house. We explained we would have to wait a long time to get our boxes but all of our things would come to our new house and she would have them again. It sounds like you won't have to wait a long time to receive your household goods, so that will be a positive thing on your side. I think discussing the concept of moving and telling her what to expect in that regard will go a long way in at least giving her the words to use to talk about how she feels or to ask you questions. I do agree that discussing leaving her friends at this point might be too much for her to handle, but maybe a week out would be good since you'd have to start saying goodbye at that point.
Your positive attitude and excitement about your move will definitely influence both your children's attitude and how they handle the whole thing. Sure, there will be times when she will have tantrums or act out but remember her vocabulary is pretty limited right now and this is a major life change, so give her some understanding but keep your rules the same.
In a nutshell, giving your toddler plenty of simple explanations instead of just telling her 'we're moving to a new house' will help her process what this will be like for her. My brother and sister-in-law recently moved and told their child nothing other than 'we're moving' and he came home from daycare one day (age 3) with his house empty and has really had a difficult time even now, over 6 months after their move. Do you have any toys at home that you could do some pretend/role play to explain it to her (small boxes, a truck, doll house)? That really helped us when we used our Little People toys (airplane, house) to explain things to our oldest during our move and a deployment.
We are a military family and know all about moving great distances - hopefully this will help!