I haven't come across a similar experience to your point (1), but here is what I might do if I were u, I think that in order for Miley to go potty outdoors during her walks, the first thing she should learn is to love being outdoors and going for walks. From what you are describing, she doesn't like it....hmmmm, Maybe start taking little treats along in your walks, praise her for walking..etc dont know the exact method in teaching her how to like her walks, but this is just one thing for consideration- associating something she loves with walking time will make her look forward to more walks. I know that in order for her to go potty outdoors, she gotta feel comfortable and happy being outdoors in her walks.
Point (2) when Crystal came to our family, snowy was a month away from turning 3 years old, but he loved Crystal the second he met her. So again, not too sure about the answer to your question. From other people's experiences, for some it takes some time until they get used to it. I hope it is the case with your two
All the best!
Kat