Puppy spoiled and has now started to snarl and snap and bite when try to take away things she is not supposed to have in her mouth

Our pomapoo(pomerian+poodle) is four months old. she is spoiled and I tried getting her back on plain kibble after my husband started giving her human food. Now she won't eat her puppy chow plain without it being doctored with human food or sauces. He tried but now she is back to getting mushy food and not plain kibble. he claimed she would starve. The worst problem started a few weeks ago. Heidi has played nicely with her toys she growls a little if you try to take her toy away but if you say give she usually complies lets you throw it our play tug. Lately she has been getting into things she shouldn't have inside and out. We live in an apartment complex and she is thrilled with the amount of trash there is to put into her mouth. The things is it used to be tough getting it out of her mouth but now it damn right scary. She snarls and snaps and bites hard. Not throught the skin but it is scary ever unlike her. She can try to dominate, but we have been trying hard on the training to sit, lay, and give. She also does other things for treats. I think she should be back on regular kibble. Her eating style is to swallow things whole she used to chew her puppy chow but now she tends to swallow it whole. I think she is afraid someone is going to take it. She is the only dog but she has two littermates and had to eat out of the same bowl. Someone suggested teaching her the drop technique now how do you do you go about doing this. Is there anyway to get the junk out of her mouth. I tried the give like we do for toys and she is determined to keep whatever paper plastic object or chewed gum she gets. I don't want this to esculate to biting and tearing skin. I don't know how to stop her snarling and snaping.  Her seperation anxiety with my husband is better but she is yet to spend a day by herself and she wil be five months this month. I think we shoud crate her and start with a small amount of time and come back. I have told my husband that in the evening it would be nice to go to a movie or a date. We both work at home so she has our undevided attention but I need her to get used to spending an evening alone. The snarling and biting is number one. how do we nip this in the bud. second how can I ever go out again and i right or my husband about justing eating her kibble and treat, not people food and adding it to her kibble so it is mushy and filled with human food. Please give me some good answers no one answered my other question and I feel like there is no one out there. Snarling and biting when she has a no no in her mouth. Unable to get it out #1#2 How to start going out on a dateand leaving her home#3should the puppy eat human food or dry kibble and dog treats. my husband i disagree. She now eats musy dog food with salad dressing or gravey or anything to make her eat because she will starve. Is there away back to good nutrition or is people food ok all the time. Help and please answer These questions this time. i am pretty desperate. I think my husband wants to spray water at her and I am not sure that is a very good idea to get her to drop her contriband and not snarl and bite.