As far as the loud sounds. Around two years of age my daughter started something similar with covering her ears at any "loud sound." Of course if she made the loud sound it did not bother her (like screeching in that high girly voice that makes adults cover their ears). At age 5 my daughter is still senstive to loud noises but she quickly covers her ears and when the noise passes she uncovers her ears. I have found it is a certian pitch, no matter the loudness of the pitch, that bothers my daughter.
To my it is all apart of growing up. They are processing so much and I think that certian pitch/noise is too much for them. I have thought of taking my daughter in to get tested but after 3 years of living with this it seems to be getting better so I will not take my daughter in. I simple help talk her through it or I tell her cover her ears because we can not avoid the noise so shs has to learn to deal with it (of course I help her learn ways to deal with it). All I did was research online and at the library with ways to help teach my daughter how to deal with what she is afriad of, I decided to skip the doctors because I do not want my daughter labled if I can help teach her skills to deal with it. Now if that stops working or does not work then I would approach the doctors.
My daughter also does not sleep well in strange places. So if I can sleep next to her or near her she seems to adjust better. At age 4 my daughter became afriad of the dark, out of the blue, so we talked through it got a LED night light that casts a small glow on part of the room and she does much better. Kids are processing so much, everything is changing all the time as they are learning more about something. Talking through all those things can help, it may take a long time to over come but every child is different.
You are in a new house, new baby, her world is changing and she is reacting to all those changes, all of which are happeneing ontop of her new level of learning. She needs to be reassured, you may already be doing this, just keep doing it and look for new ways to reassure her about all the changes. I spent TWO night sleeping in my daughter's room when we first moved to show her it was ok. I told her I will sleep in her ONLY two nights so you know it is ok, and then a few years later we had to get a night light. It is not easy for you and it is not easy for her but hopefully in time things get better or you both learn how to deal/live with it.
Hope you get answers and ways to help your daughter. I recommend the book Highly Sensitive Child too, it really helped me understand my daughter better so I could help her in ways that worked for her. I really had to throw out everything I was doing before, which was hard, but changing the way I apporached things helped my daughter.