Hey Adi, Welcome, great choice on selecting this breed.. they're really awesome.. I've had my pup for only a month & it feels like I just got him yesterday! OK, now answers for your queries
Is it better to choose a male or a female GSD puppy?
Doesn't matter if you don't want to breed or anything
What do I need when it comes to crates, etc?
Get the biggest size crate available if u intend to keep him in the crate throughout his life.. get crate dividers so as not to give complete access when he is a pup.. Ideally he should have enough room to stand, turn around & lie down..
Is it too difficult to teach a dog on where to pee/poop?
I won't lie.. It has been a little difficult with my pup since I also live in an aptmt & taking him up & down everytime isn't feasible hence it takes me sometime.. but since u say u have a yard, should not be much of an issue.. usually they pee after waking up, after play, and any other time they deem fit to pee! as for the pooping, u have to watch his schedule.. suggestion, keep him on a fixed schedule rgdg his food.. it'll be easier for u to know his poop time..
What kind of a leash should I have?
Since u'll be getting a puppy at roughly 7-8 weeks I assume, they don't need a leash.. U won't be able to take him out anywhere till he's completed his vaccination so doesn't matter.. u can start training him immediately off-leash in your home & that saves u the trouble of double effort (on-leash & off-leash)..
Also what about ticks and measures against them?
U have tick powders available in the market.. there are also solutions like Advantix (not to be used for pups under 6 months of age).. U can ask your vet rgdg injections against ticks/fleas/de-worming/anti-fungal (not to be given to pups under 6 months of age).. as of now, only the powder..
but I really wan't to be prepared and not make any mistakes
LOL.. U will! And we all learn from them.. nobody's perfect especially since ur getting a puppy.. read as much as u can & it still doesn't seem like enough! take care..
PS: Please research on a good breeder before you buy the puppy.. Also, find a decent vet in your area to save u the heartache later of switching vets in an emergency..