Two myths about crating/housetraining

I hear these a lot, especially from experienced dog owners and it's common internet-advice.  There's some truth to the statements, but there is enough danger that it is important to be cautious.  There are exceptions to every rule.

Never let a barking puppy out of his crate!
The piece of truth:  If the puppy/dog is barking to get out of the crate or to get attention, the approach and release from the crate will reinforce the barking.  The dog will learn to bark to get let out.  If you wait a while and then decide to let him out, you teach the puppy/dog to bark longer or with greater intensity.
The big picture truth:     It's not appropriate to let a dog/puppy bark for a long period of time, especially if it is a very distressed barking or if there is anxiety.  It's inhumane to let a dog be screaming and vocalizing out of distress.   Many new dog or puppy owners are not able to tell the difference between "I want out!" and "I think the world is ending" barks.    If you let an attention-seeking puppy out for barking.... he will bark more.   If you continue to ignore a seriously distressed puppy, you could be creating bigger problems.  
What to do:  Be preventative.  Don't let the dog or puppy get to the point where he is barking and/or distressed.  Gradually work up to teaching him to be contained. If you have to be gone, -beforehand- test out other containment strategies. This could be an exercise pen or a small room with gates/doors.   If you -know- your dog is bad in the crate....we need to gradually work up to him being contained.  Consult an appropriate professional.

My puppy is peeing in his crate. I need a smaller crate!
The piece of truth: Most puppies to not like to sit in their pee. Many do not eliminate in their bed area.
The big picture piece of truth:  Take your puppy out more often. If you have a puppy who doesn't mind sitting in his pee (...seems more common with some shelters and pet store puppies)...use the biggest crate you can. He has the -option- of sitting somewhere else.  With a small crate, he has no choice.  With these puppies you have to be extra diligent about the trips outside and reinforcement.