Congratulations on the puppy!
For the pooping problem: have you tried to run her around a bit, maybe a quick game of fetch or a quick game of chase? That will often get the bowels working. Also, I wouldn't recommend you staying out with her for an hour in the hopes that she will poop. Puppies her age are very easily distracted by lots of stuff outside, sights, sounds, smells. And, really, after a few minutes, they usually forget all about the fact that they are supposed to go poop. So, by staying out so long, you really aren't emphasizing that you are there to potty. If you're allowing her to sniff around, and explore for an hour, the goal isn't clear to her.
You need to differentiate between potty time outside, and "free" time or play time outside. If you are combining both, in the beginning, it's confusing. So, take her out for five minutes, say the same magic potty words. After 5 minutes, if she hasn't pooped, take her back inside, BUT, not for good, just for 5 minutes, before going back out to try again. During the 5 minutes inside, keep your eyes directly on her, and stay close to her, so if you see her start to sniff or even start to squat, you can interrupt her and rush her out. Basically, alternate, 5 minutes out to try, then 5 minutes inside to wait before trying again.
And, clean up any stain with an enzymatic cleaner.
As for the biting, that's the way puppies play. It is similar to how toddlers have to put everything in their mouth!
If you've only had her 5 weeks, but you've tried the yelping, turning your back, pinching the back of the neck (yikes, don't do this any more!), growling, etc, then it seems like you've confused her by trying too many methods without giving any one method the chance to work. Think of it this way: you aren't just trying to get her to stop biting on any ONE occasion, you are trying to teach her a skill for the rest of her life (bite inhibition). And, longterm teaching takes time.
If you stick with this method, and everyone in the house responds in the same way, EVERY time she bites, it should start to gradually get better:
- puppy bites, you make a noise to let her know you didn't like it. Many people recommend yelping, but, for some puppies, that can excite them more, and make them bite more. You might try saying OUCH loudly but not angrily.
- the noise should startle the pup, and get her attention.
- the pup will probably bite again, as it's second nature to her, so make the noise again, but this time leave the room for 20-30 seconds, and do not allow her to follow (helps to go into a room where you can shut the door so she can't follow you.)
- repeat, repeat, repeat. As many times as she bites, do the noise, then the noise + leave the room.
My fiance hated this puppy stage, as it interrupted his tv watching time, with all the getting up and leaving the room, but, it did work! One thing to keep in mind: our first pup took 4 weeks to stop biting, our second took about 1-2 weeks, and our current foster pup took about 3 weeks. So, once you start a method, and stick with it vigilantly, it will take time.
As for the humping: discourage this. It isn't sexual, humping can also be a form of puppy play, and also occurs when a puppy is over excited. So, the walks will help this, too. When she does this, distract her, and get her interested in something else. It helps if you keep a leash on her inside, as you can direct her attention elsewhere pretty easily, and this will help her get used to the leash for walks. The thing is, most dogs will consider unwanted humping to be rude behavior, so you don't want her to get in the habit of doing this!
And, for your older daughter: kids move quickly, often times, and in ways that seem spontaneous or without warning, they also speak in higher pitches, which can be exciting to dogs, and are often louder than adults. What you describe doesn't sound aggressive, towards your daughter, it sounds like she is trying to play with your daughter the way she would with another puppy, as growling, snapping, and jumping are all puppy play behaviors, and it's pretty rare for a puppy that young to truly have aggression issues.
To compound this, a child will usually squeal, or run, or jump around when a puppy jumps at them or snaps or something similar. If this happens, the puppy thinks "cool! game on!" and will keep trying to play.
So, part of it is teaching the children to behave calmly, and walk away, to another room, for a few minutes.
Puppies really love and crave human contact, so losing that contact when they are too hyper can really calm them down quickly.
You can also have "time outs" for the puppy, but I wouldn't recommend using the puppy's crate for this. Maybe a puppy safe room like a bathroom or laundry room where you can shut the door for 30 seconds to a couple minutes.