I'm not a lawyer, but going to hit questions one at a time here. As a user of an owner-trained service dog, these are just from my research.
First off, excellent for Zhi!
Alert tasks can be really, really useful.
Firstly, you need to figure out if you're legally disabled. (Substantially limited ine one or more major life aspects.) For eample, my upstairs neighbor is diagnosed with depression, but she takes meds for ti (and responds to them) and it doesn't limit her at all. Even without the meds, she's still not 'substantially limited'- she's just depressed all the time. She still dated and worked and took care of herself, etc. My depression *is* substantially limiting- when I'm at the downswing, I don't respond to meds, I don't have enough energy to take care of myself or do the things I need to do. So while your hearing impairment may be severe enough, it may not- I have a friend who is profoundly deaf who is NOT 'substantially limited' enough to qualify as disabled, despite the fact that he gets accomodations from his workplace- his hearing aids are all the asistive tech he needs, a dog wouldn't do much for him except when he doen't have his aids in and he uses other stuff for those times.
Yes on the more obedience. I have a personal opinion that any SD should be able to qualify for their CD (not just a CGC) without a problem. This is, however, just a personal opinion- but a dog who can get their CD has at least a fundamental grasp of manners, IMO.
There is no official certification. There are sham agencies (like SARA) where you send them your money and they end you 'official' documentation, but
certification is not required under the ADA.
Here's where it gets tricky: Service dogs in training aren't covered by the ADA. You may, or may not have public access rights with a SDIT. In some states, only the trainer does (and owner trainers count in some states, but not in others), in others, only a puppy raiser does, and in yet others, no dogs in training have any access except that granted at the whim of the individual store.
I would *NOT* be putting her in a purse- it looks bad, frankly, and you'll get more people assuming she's a fake SD (most toy breed dogs in purses with people claiming them as SDs *ARE* fakes, IME)- she's big enough (if she's normal crested-size) to walk on her own and be tucked under your arm in a crowd if you really worry about her getting stepped on. You *will* get access challanges, even with a patch bigger than your dog. What they are allowed to ask is "Are you disabled?" "IS that your assistance animal?" and "What tasks does she perform?". That's it. Anything else, you can tell them to please call the police, you'd like to file a complaint.
Additioanlly, how is she going to alert you from the bag? She probably needs to be able to move more to do that?
With access challanges, I've found it helpful to actually role-play them with folks for practice.
gatekeeper: "Hey, you can't bring that dog in here."
me: "He's a service dog." *smile and keep moving- note I didn't explin my disability, didn't offer to put him in a bag (it'd be a big bag, for Mal!) and didn't offer to leave and come back without him.*
gatekeeper: "You don't look disabled/you don't look blind/what's a service dog/what does he do?"
"That's right (as syrupy and chirpy as I can manage it, on a good day. On a bad day I ahve been known to mutter things like "Well, you don't look dense, so obviously one can never tell.")/a service dog is a dog who is trained to assist a disabled individual, including but not limited to guiding the blind. there are many types of service dogs."/ and/or (if I think they are asking about tasks "he reminds me to take my medications, helps prevent me from getting disoriented, and alerts me to sounds I don't notice." )
Please DON'T (even if you get one) produce a letter or 'official SD ID" of any sort. They're not required by the federal government, and it sets up the gatekeeper to expect the same from future SD users who don't have to have them.
Sham85, 'hearing trouble' is too inspecfic and may or may not hold up in court. I have hearing problems (CAPD) BUT they're neurological and wouldn't qualify me as hearing impaired. (It's processing that's the problem)
Additionally, I think you may want to think NOW about what you will do in bad weather. Obviously a bag would help, but how will Zhi stay warm, etc, if she's out in public with you?
You may want to come ask these questions over at ServiceDogCentral.org - it's a really great forum with good critical discussion and lots of knowlegable folks.