We did things a little different here and introduced a new protein every three days. Only did it this way because my main contact and experienced raw feeder said that after 10 years or so, she's never had a dog that reacted badly to the fast switches. She fosters and have owned many pooches. Although she did say that it may be different for senior dogs, they're stomachs are more sensitive. Punkin was 4.5 yo when he started and he did fine with the 3 day switches.
As for the beef bones, yes, I'd be careful with that like Lauren mentioned. Heck, I'm so scared of them that I've never fed the boys any. Same with pork bones, it depends which part of course. Just remember never to give weight bearing bones, unless for rec purposes. And watch them when you do give them one.
And ditto about raw vs processed chicken. You can always try and give them some quarters and see what happens. Although chicken allergies do exist, it's rare in the raw form.
I'd aim for 2% of adult body weight for now. So for my guys it's around a pound. It's better to feed them a smaller amount in the beginning to avoid runny poops. Eventually you can add a little bit more if you find they're losing weight.
Also, like Lauren said, you can always prepare a ziplock full of meat that your mom can give and leave it in the fridge. For breakfast I give the boys something boneless, like green tripe, beef or pork heart, tongue etc. These are simple to give and create very little mess. your mom sounds wonderful btw, good for her for loving her fur-grandkids so much.
