Maybe for your Dad there's a household chore you can do as part of the deal.
As you are moving into a new room before you get your bird it's a great time to make sure the new room is bird proof. Make sure there's no gaps down the back of wardrobes etc. where the bird could fall, making sure there's no wires hanging around that the bird might nibble and any high places he's likely to land have some paper down for any mess.
As you're getting a rescue bird, the people at the shelter should be able to advise you on the birds personalities somewhat. There may be one that is more loving in nature. I personally wouldn't worry about gender too much if you can get a friendlier bird.
My Sidney was a female and she was very affectionate and often came over for her head to be scratched and loved human company.
As for the allergies your Mum has, just clean often and it shouldn't be too bad. Offer the bird a bird bath if it wishes to use one. If he doesn't like it, you an try misting him to see if that helps.
Good luck.
