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My next question would be: what do I do if, even though I have goodies (although she's not very food-motivated at ALL) and I call her with the happiest, most excited cheery voice possible, she still does not come?

You've just gotta find the right motivator - whether it's really stinky cheese, a ball, a squeaky toy, a tug toy, or something else. Trading all of these things off during a training session works well. Also, don't forget that since you're holding and playing with the toy, it's automatically valuable to her.

Another also: food as a training treat works much better before dinner than after.
From what I have read, it's a very, very bad idea to let her "get away" with ignoring my commands.

It's not really a matter of her "getting away" with anything, it's more a matter of not letting her make repeated mistakes that can become ingrained. If she's not getting it, wait for a better time when she may be more focused. But, before you quit, ask your dog for something that you know she can do (sit, fetch, etc.) and reward her profusely.
And don't make your training sessions very long - a bunch of short sessions is better that one long one. Try to end on a positive note - too many people want to keep on going because the training session has been successful and only stop when the dog starts to shut down and makes a mistake.

Matt. Rocky's a Dog.
From what I have read, it's a very, very bad idea to let her "get away" with ignoring my commands.

It's not really a matter of her "getting away" with anything, it's more a matter of not letting her make repeated mistakes that can become ingrained.

It *is* a very bad idea to let her "get away" with ignoring a command. But for the dog to be ignoring a command, it has to understand what is expected, and choose otherwise. IOW, a puppy just learning a behavior can't, by definition, ignore the command for that behavior.
If she's not getting it, wait for a better time when she may be more focused. And don't make your training sessions very long - a bunch of short sessions is better that one long one.

Simple recall - touch your finger lightly to the puppy's muzzle, squeal, run away. In theory , the puppy should follow you. Wah-la! Good puppy! (NOTE: no command is given.)
Another way of bringing a puppy to you: focus intently on something on the ground or on a small toy, make happy-happy-I've-got-a-WONderful-toy noises, and see how long it takes the pup to come running. Again, no command is given.