Frosty501

Hi My grandfather recently passed away and i have inherited his african Grey "Johnny" who is 28yrs old. I am 30 so known him but not looked after him. I am having a trouble trusting him as he has always been more favourable to men than women and bitten me a few times. I am in a wheelchair and having a high cage i could never try reach him with out him biting me. i have since lowered his cage and he now climbs onto my hand and lets me scratch his head. For years he has been plucking out his feathers and i cant seem to get him to stop. I have changed his diet as the vet suggested, given him toys to play with so it can keep him busy but he hasnt stopped. Is this just a bad habit now or is there something more i can do? He cannot fly but i do let him out of his cage to climb around on. I dont let him walk around the house as i have a jack russell that would munch him given the chance. how can i stimulate him more and gain confidence in holding him so he doesnt bite me. He has a terrible habit of squawking in a very high pitch. Any advice would help.... i have read a number of posts on "panting" and other behaviour.:confused::confused::confused: