Dogs typically become very possessive and protective over what ever it is that they are tied to. Making them "sit" or "lay down" will help to desensitize them to noises or movements that make them "protect/alert you".
Eating the bird, pretty normal. My pitbull ate a baby squirl. Dogs sometimes do that sort of thing.
Potty Training- because they are older it may take a little longer. Just like ppl animals get set in their own ways, but it absolutely can be done.