Fears for Ahren

Now that I have hope that Ahren will eventually join our family, I am hit with thoughts about what it will be like to bring a 2-3 year old child home. It will be completely different than bringing home the 8-10 month old baby we were expecting. I know that he is developmentally delayed. At 10 months old he could not sit unsupported and even had trouble holding himself upright with support. He could not bear any weight on his legs. He had difficulty eating from a spoon. Now at 17 months old he is still not walking. These are the things I know. What I don't know is why he is delayed. Is it because he is never put down so that he can learn these skills or is it something else?
I also know from my visit in October that he has a quiet, sweet and laid-back personality. I know he learns well because I taught him to wave bye-bye in the few days I spent with him. He also reacted to me calling his name by turning and looking at me smiling. These are good signs.
I am visiting again in two weeks. On this trip I have decided not to keep Ahren at the hotel with me. At 18 months old, he is completely attached and dependent on his foster family. Separating him from them for a few days would cause him too much pain. It would be selfish of me to do that, especially since there is no chance that he would remember me from this visit by the time he comes home. Instead, I have arranged with his foster mother to have her bring him for visits. He will have her there as his comfort source, and I can spend time with him and get to know him.
I keep thinking about how it will be to separate him from the only life, the only family he has ever known at an age when children are trying to exert their independence but also need the security to do so successfully. Because we will have 4 other children when he comes home, will that help him be comfortable or will he feel lost in the crowd? (His foster mother has only grown children.) He will have developed language by then, so he won't be able to communicate with us or us with him very well. How do you soothe a child that you cannot explain things to?
My plan is to take it very slow. We will bring him home to a quiet (or as quiet as can be) home where we will not have visitors at first. We will spend time holding and rocking, playing on the floor and exploring his new surroundings. We will take it at his pace. We will watch and learn from him as we go. With his personality he could adjust easily and fit right into the family, or it could totally overwhelm him. We will just have to be very careful in what we expose him to in the beginning.
As we get through the adoption process, and we come close to the end, I will visit as often as I can so that he will know me. I don't want to be a complete stranger. Already, his foster mother shows him pictures of us every day and refers to us as Mama and Papa. I will send more pictures and little gifts (which I already do each month) so that he has some concept of us. I need to find out if they have a VCR or DVD player because I can send videos of us for him to watch.
It is so strange to me to think we have loved this child with all our hearts for so long, and he has no idea we exist. Can he feel our love on some other level? Will that love be enough to help him through this adjustment time? What if he never loves us back?

None of this really matters at this point since we still have a very long and difficult road ahead of us. I just can't stop thinking about what it will be like to finally be his Mommy.