The right dog of either type, German show or working, could be a perfect dog for you. And there are dogs within both types that would be poor fits as well. It will come down to the individual breeding/litter and individual puppy within that litter.
Yes, you can find black/tan working lines. Though they will often be darker, with more black and less tan. Often referred to as melanistic or "blanket pattern" black/tans.
You are not looking too early. Many good breeders have long waiting lists, so starting your search now for a puppy middle of next year is a good route to take. Especially since you're still in the narrowing it down phase.
My recommendation would be to contact training clubs and groups in your area. There are a lot of SchH/IPO clubs out that way, and most of these clubs will have both working and show line members. Reach out to them, ask to visit a session or two (most will be open to you doing this). If there are any trials, shows or other competitions in the area maybe attend those as well. Visiting the clubs will give you the chance to meet many different dogs of each of the types, and talk with their owners, so that you can get a better feel for which type would be the best fit for you personality wise. In doing so, you'll also be able to network with GSD people in the area and they will probably have recommendations for local breeders based on what type of GSD you decide you want (or at the very least they can tell you who to avoid).