Another word about housebreaking. The smaller the dog, the smaller the bladder. The little guys simply cannot hold it as long, especially in puppyhood. For several weeks (unless you have a very smart learner and are planning on using puppypads) he or she is going to need to go out every couple hours…all day, all night. You will be sleep deprived, and there will be accidents. You will need more than a week. But, if you do it right (that is, consistently) the first time, you won’t wind up having problems later on. Really consider adopting an adult…there are thousands of them, mix breeds and purebreds too, on petfinder.com. and at local rescue orgs. You may have accidents at first anyway, because of the stress of the move, etc. Dogs go to the bathroom in the same area over and over, so, regardless of the age, I’d buy some Nature’s Miracle in advance (it has an enzyme that destroys the pee smell, so the dog won’t go to the bathroom again in that spot should you have an accident in the house). They also make “pee posts,” a stake that attracts the dog to go to the bathroom in the lawn near where you plant it.
Also, don’t assume that just because the dog is small, it doesn’t need to be socialized. This is critical for dogs of all sizes. Enroll in a puppy class (Petsmart has a great 8 week/8 class program for $109 that’s guaranteed) and do some reading about positive reinforcement-based obedience. Do not use punishment-based methods.
I’ve worked as a dog bather for a year, and I cannot tell you the number of small dogs that had never been socialized to a) be around other dogs b) be around people other than the owner and c) be comfortable with the whole grooming process. Even if you plan on doing all the grooming at home (which I do not recommend with the breeds you listed and no prior experience), the dog still should be socialized for all of these situations because you will need to take her to the vet, possibly board her, and you’ll want her to behave when meeting new people/dogs.
If you are considering either a westie or a pom, those grooming needs will be medium to high, and probably higher than you are anticipating. Brushing every few days layer by layer, (not just over the top with a slicker brush, which will miss any matts) plus haircuts/baths; this is not just to make the dog “pretty.” Inadequate grooming can lead to matted fur, which can lead to hotspots, which can lead to infections, nasty smells and tons of discomfort for the dog. Professional grooming is not cheap (nor should it be–hair cut, bath, blowdry, nails done, anals expressed…all with the risk of being bitten, pooped on, barked at incessantly [I <3 my job]). And be sure to tip your groomer/bather :).
As far as the grooming stuff goes, start early (before 4 months) even if the pup doesn’t need it yet. Handle its paws–A LOT. Otherwise, you’re going to have to go through hell when you have to have her nails done the first time. Get the little one used to having shiny things (like a spoon) around its face so that clippers/shears aren’t as scary. Expose him or her to loud noises (like your blowdryer). Also, ask you the dog groomers if they offer special puppy packages (they often do) which will slowly ease the puppy into the process, but not have you shell out extra money for a full service groom the pup doesn’t need yet.
You might also need to know that poms (and a lot of other small breeds: pugs, English toy spaniels, yorkies, toy/mini poodles, shih tzus, etc.) should not be muzzled with anything other than a basket muzzle (the kind that look like the thing Hannibal Lecter wears in Silence of the Lambs) because they are prone to breathing problems and can die if their ability to pant is even slightly restricted.
