It takes a while for the bird to get used to you. It only bites in fear or anger so it is not used to you yet.
Birds don't have HIV. The clue is in "Human Immunodeficiency Virus".
The 'talking' also comes when it feels at ease, although the Greys often pick up words from their parents while they are being reared. Once it starts talking you may wish you very tought it to.
Yes, they can be 'toilet trained' by rubbing their botty every half hour while they are out this will stimulate them to void. If you plan to teach them this you must do it at a set time and always in the same order; let the bird out, on top of the cage, rub and cr@p. In no time you won't need to rub anymore. While it is out, every half hour you must go for a tissue so it knows what time it is. To have any success with any parrot you must remember that they are very much a creature of habit and do not like change.
To punish the bird for undesirable behaviour get a smaller cage and if it doesn't respond to a firm NO, put it in that cage for 10 minutes and make sure the cage is on the floor behind the couch or chair. Not responding to a rub is NOT bad behaviour as this is foreign to them and can only be encouraged with positive high voice praise and reward. Don't use this for every willy-nilly thing it does that you don't like as the key to training is patience, repetition and one sunflower seed as a reward. Never let the bird dig into your pocket to steal some seeds as this will undo months of work, no matter how cute you may find this.