If the ones she was around didn't like her, then she might not have been able to learn just how a cat should act.
Except that it sounds to me like she is
acting like a cat. Cats like to be around people, and it's common to follow them around. They don't all like sitting in your lap or being picked up, but I think every cat I've had has wanted to be in the same room with me. Some will meow if I'm somewhere else. My current cat does this, and all I do is call out his name and he shuts up. (It's like he wants to make sure I'm there or something.)
"Mawing" is perfectly normal. Some cats do not cover up their business in the litter box, and I've seen them paw outside the box. I've seen them paw outside a food dish too (especially if they're unhappy with the food).
Cats most definitely attack birds. It's not uncommon at all to leave them suffering. (Sad, but they do this.) I'm not quite sure why they don't finish killing them and eat them. Either because they're being fed by us humans and don't need the food, or because being domesticated and fed easy food for so long has either made them lazy, or even made them forget what they're supposed to do. (My one cat does sometimes chomp the heads off mice -- and then throws it back up.) But regardless, this is not uncommon. She doesn't know she's leaving them suffering -- it's not like she's being "bad." She's being a cat.
Becoming more wild from being outdoors -- don't know if I'd consider that "common," but it also doesn't surprise me. She's not really being quite as "domestic" by being outside -- she's more reverting back to her normal (wild) state. So it's not a surprise. And being timid of other cats -- very common.
Cats also like routine. They like it a lot. Some cats react to changes more than others, but they don't like change.
Rather than sounding like something is wrong with her, it sounds like you don't know how cats act.
Unless something becomes extreme or harmful in some way, as far as I can see, she's just acting like a cat. They are pretty odd sometimes and that always surprises people who aren't used to them. Those of us who love cats, their oddness is part of what we like.