Phew, there's a lot going on here but I assure you, it's solvable :)
The biggest one - she still bites. She's mostly grown out of it with me, DH and our sons (teenagers), but she goes for DD (10) in a way that's playful but also perhaps wanting to dominate? She grabs DD's clothing and drags it, growling. She also barks at DD. DD adores her, and gets quite upset. To be fair, it's a few weeks since she last broke the skin, but she's still prone to these behaviours.
She's so, so young still. Mine didn't stop mouthing/biting until he was about 9-10 months old. Honestly, you have so much time! But your dog doesn't want to dominate your DD - she's just a dog. I imagine her behaviour is an attempt at play/attention but obviously it's not the right way to go about it. Get your DD to fold her arms and turn away every single time. No shouting, no eye contact, just fold her arms and ignore. If she's calm/well behaved, then you can reward :)
-She growls when you try to take something off her which she shouldn't have. Once, when DH took something off her, she nipped his hand and drew blood.
Resource guarding. Please don't try and grab things off a dog that guards, it won't end well. It can be solved with a behaviourist but in the meantime, teach her to drop the item for some food. Get the dog to come to you for something yummy (chicken, cheese, sausage) and then you can safely retrieve the item once she's in another room. Your DH got bitten because he ignored the warning signs - some dogs will let you take anything, but yours obviously isn't that kind of dog - please get a behaviourist in to deal with this.
-We haven't crate trained her. She sleeps - generally very well, to be fair - at DH's feet (he has to sleep downstairs at the moment anyway, for various reasons).
Not a problem. My dog is 2.5 and has never slept in a crate. So long as you're all happy with the arrangement, it really doesn't matter if she's not crate trained, I promise.
Any sound at night and she's up and barking (temporarily - she settles when the sound stops).
Normal, but obviously annoying! What do you do when she does this?
She takes quite a while to stop barking at new people. Since it's been allowed, we've been gradually introducing her to both adults and children, and she is now getting quite a lot better. But I worry that lockdown (which spanned her greatest socialisation period) may have really hampered her.
Just keep doing what you're doing and you'll get there. Lots of slow, gentle introductions, lots of rewards, and pay attention to her body language so you can remove her from the situation if she she's unhappy.
- DH and I can no longer trim her fur - she now tries to play and snap at the scissors/clippers too much. We're willing to pay, but I'm scared no one will be able to groom her as she's too hyperactive and can nip. Have a "puppy appointment" with a groomer next week.
Get a groomer in until she's a bit older. You need to desensitise dogs to grooming and this is best done by a professional imo. With time you should be able to do it yourself - try to spend time touching her ears, feet etc. and rewarding her for staying calm.
Honestly - 99% of this is totally normal puppy behaviour - it just feels very overwhelming at the time! My dog had me in tears numerous times when he was younger - and all the behaviour I worried about no longer exists. Just put the work in, take her to training and be consistent and you'll be rewarded ten times over. Honestly, please don't worry! 