I'm sorry you're going through this with Jade. From what you're saying, the plucking isn't brand new. Please read through the following link, you may find some helpful advice. As wonderful as quakers are, they are prone to plucking and QMS.
http://www.parrotforums.com/behavioral/52217-plucking-search-answers.html
I wouldn't consider getting another bird to solve Jade's issues, there is no guarantee it wouldn't make the problem even worse. The aggression could be due to hormone levels among other things. Personally I would make an appointment with an experienced Av Vet and get Jade a thorough exam. Many may disagree, but I would hold off on the wing trim at least until Jade has seen a vet, if the vet agrees a clip would be a good idea, then I would let the vet do the clip.
I would never approach a bird with gloves, least of all a quaker. A better suggestion is to keep Jade off your shoulder until you have successfully trained him not to bite. With quakers, it's good to work with them away from their cage, a playstand or portable perch.
Jade needs to see that sitting on a human perch is a privilege, not a given. If Jade bites, do not react with drama, quakers live for drama, if you have a talker and aren't careful with your methods, your training can go south pretty fast, before you know it, your bird will bite you and yell Ouch for you. Instead, immediately return the bird to a designated time out place, lean down so the bird is off balance and choose a command to use every time, Step Away is our command. Step Down or Step Away takes practice, it's usually difficult for birds to climb or step down. Wait until the bird steps down, then turn your back and quietly walk away. Have a treat and word rewards ready for when the bird flies back to you. Repeat as often as necessary. Three bites in one session was my personal limit in the beginning, after that the offender went inside his or her cage with the door closed. This is only one method and it requires consistency to be successful, but once learned it's an ingrained behavior. Some quakers respond well to clicker training, I personally prefer voice commands but use what works for your own little green dragon.