One way to get that stringy, falling apart consistency for your meat, be it chicken, pork, or beef - bake the meat first, with minimal seasoning. Then take your cooked, deboned meat, and cook it again, in a seasoned sauce, while stirring roughly. This will not only have the meat falling apart into fiber bundles, it will make sure all the bundles are well-coated with your seasoning sauce. I set up my sauces so that I can reduce them to a paste to go with the meat, but some people prefer a wetter meat.
This method works very well with so-called poorer cuts of meat - beef chuck, or pork butts. The first baking will get most of the fat running off the meat, and the second cooking makes it very tasty.
For refried beans, I think that the best way to get them good is to make them yourself from the dried bean.
ETA: This recipe is based on a one pound bag of dried beans, adjust as necessary.
Soak your beans overnight. Rinse, and throw out the rinse water. Then I stick 'em into a slow cooker on high for 4 hours minimum. More can be better, but don’t go too wild. When you’re find that stirring the beans has them starting to fall apart in response to the spoon being dragged through them, they’re ready.
I begin with a large, sweet onion, and saute that in olive oil. Lard is the traditional fat, but I found it wasn’t adding much taste, and I have olive oil - and that keeps better than the lard for me. I like chunks of veggie in my foods, so I chop it fairly coarsely. Then, if I’m making these for myself, I mince, finely about six or seven habaneros. For less masochistic types, I’d mince in about that number of jalapenos. Then add a little salt (no more than a tablespoon) and if you want it, a little generic taco seasoning. (Or you can work your own taste mix with cumin, paprika, and ancho powder. I’m too lazy to work that out, myself.) Then drain the beans, and add them to the skillet. Then using a stiff spatula, mash everything together. You won’t get all the beans mashed, but most of them will. And unless you’re cooking for a large family, you’ll have plenty of left-overs. But they’re yummy, and they reheat well.