Owen Mumford ships promptly. They should be available from any pharmacy, either in stock or by special order. If you have never seen any pens, you might either ask your diabetes educator to show you some, or go to a medical supply store that carries a lot of diabetes supplies and ask to see them. I am visually impaired. See Question 2.
Some people advise against leaving pen needles attached to the pen between injections.
However, I have done so ever since starting to use pens a decade ago and have had no problems. You can recap the needle when you remove it and reuse it, just as you can safely reuse syringes. If you reuse your syringes for weeks, you can reuse a PenNeedle for weeks. I know people who do that, and I know of no reason it would be unsafe, as long as you are really careful about not introducing contaminants into the cartridge. If you use Lente or Ultralente insulins, you may have a good reason to make your own cartridges.