Hi Bumble I can answer some of your questions.
Don't worry about weight so much. I know that HVs in the UK put a LOT of importance on it, but there are other things to look at, especially in a BF baby to determine if they are getting enough. Dirty diapers are a big one. As long as she is giving you lots of wet and dirty diapers, then you know she is getting what she needs. 8 a day is good, but if she is anything like my son, it will be many more. So don't let the HV worry you too much. Plus most HVs use a chart that is for bottle feed babies, who gain weight differently than BF babies do.
Is she alert? Is she happy? I know you worry about her being unsettled, but most newborns are. They have a huge adjustment period to go through to get used to this big, bright world of ours. She is used to a climate controlled, 24 hour womb service, nice and dark. I can only imagine how crazy the change must be.
The clicking and wind are probably related. I found this on Kellymom, and it sounds like what you are experiencing.
https://www.kellymom.com/bf/concerns/baby/clicking-when-nursing.html
If she is breaking the seal of the latch, then she will be sucking in lots of air. It may be hard to see since your breasts are larger, hence the reason she doesn't do it when having a bottle. Also, remember it is easier for her to get milk out. Bottle nipples will flow much faster, she doesn't have to work for it, like she does with BFing.
Overactive letdown:
https://www.kellymom.com/bf/supply/fast-letdown.html
I am not sure how old you LO is,but comfort sucking is a very normal behavior. She probably just wants to be near you more than she is hungry, which is why she won't settle for your DH. Daddy doesn't smell good like mommy does.
I only have one, but I can imagine how hard it must be to try to divide your time between a todder and a newborn, they both need you. Have you got a sling or a carrier? Preferably one you can get your LO to nurse in? This way you can have her near you and hang out with your toddler, or cook or get stuff done around the house. I found that the Bjorn worked well for us when Brenn was tiny. I could lower the straps down far enough, get him latched on and get around.
BFing is a learned skill, for both you and your baby. It's not something that happens all at once, and can take some women a few weeks to get right. Don't feel bad about that. We have gotten away from BFing as a culture, and no longer have the support that we used to. Think how a few hundred years ago, every woman around you would have BF, and you would have easily had them to ask questions of. Now, very few of us have that. I know I didn't when starting out. My mom only nursed for 6 weeks as she didn't have support or help. I have no sisters, or cousins and the friends I have don't have kids. I found through the La Leche League, support and help, you might look into a chapter near you. Its really great organization.
I hope I have answered some of your questions. You are doing wonderfully hun. Just have confidence in yourself. Tell your DH and family this is very important to you and you want and need their support.