Doberman Pincher and Akita..

Opposite sexes are usually better. 

There is a poster that has Akitas (i can't remember their name though) who can tell you a lot more than I can.
 
From what I remember, (and experience) Akitas were fighting dogs in china, so they can have aggression problems with other dogs- so I would get the pup when it's young and socialize it very well- to people, other dogs, cats, etc! I believe they have a similar temperment as a chow, but don't quote me on that.
 
Akitas are a very dominant breed and must have a strong handler who will show them who is boss or they will take advantage of you. Many Akitas that we get in the groom shop are very undersocialized and we have told at least 3 owners that they can not come back due to aggression to people. (we love the dogs we groom, but the safety of the groomers comes first).

I would get a female, from a REPUTABLE breeder- who breeds for temperment. Meet the parents of the puppies, and see their temperment.
 
Does your mom's dobe like other dogs? Would he be resentful to another pup? If you get the breeder's okay, I'd introduce the dobe and the pup on a neutral location, so that the dobe doesn't have to feel like he has to protect his territory.

Good luck and welcome to the boards!!
 
 
 

My mom's pincher is very friendly with people and pets.
The problem is that my mom trained & raised him with TOO much love and he always had whatever he wanted. Although, the pincher's owner is my mom, not me. And the Akita's owner will be me.
I don't know though if they will live peasefully in our house.

Gina was the one who bred and knew much about Akitas. Unfortunately, I believe she's left the board. There were other members who had Akitas, but I don't know if they're still around.

To OP: My dog's mostly Akita, and the poster above is right that Akitas can be headstrong and dominant ('cept that they're from Japan, not China []) so intense socialization is a must. It's very easy for Akitas to be dog aggressive, and oftentimes an Akita's posture also gives other dogs a wrong signal that inflicts fight. It'd certainly require lots of time and effort, but I'm sure it'd be worth it, and certainly not impossible...

Akitas are a very dominant breed and must have a strong handler who will show them who is boss or they will take advantage of you.

 
Rather than show them "who's boss,"  you should show them you are their benevolent leader. (I know it means the same thing... but saying 'show them who's boss' makes me think of alpha roles and being physically abusive toward the animal, even though I know that's not what you meant [])
 
I grew up with an akita, and she was a dominant personality towards our other dog (she was not aggressive, just was comfortable in her place). She was extremely gentle with me and my brother though and never 'dominant' towards anyone else in the family. She was, however, extremely protective if she thought we were in danger.
 
 
Just remember, research, research, research. Get into a good puppy/obedience class and socialize, socialize, socialize.

Gina still posts at ourdogsonline.com if you want her advice.
Akitas are not the most dog-friendly breed, and usually become quite aloof by the age of two. That said, I do have one that comes to my play group still, and he is past that age.  BUT, his mom spent hundreds of dollars bringing him to positive reinforcement classes from the time he was a tiny pup, and she never stopped socializing him.  It takes money, time, and dedication to devote that much energy into creating such a good dog, and it is probably also a credit to his unusually stable temperament, too.
Dogs of opposite gender and with an age spread usually get on better, but it's no guarantee.  They pick their friends just like we do, and dogs that get along when one is a juvenile may not get along so well when the pup grows up.  Also, you didn't say whether your mom's dog gets along with strange dogs or not - remember that getting along with packmates or dogs they know is way different than getting along with strange dogs.  The good news is that most adult dogs are tolerant of very small puppies, so sometimes it is best to get a wee one.  If you are a first time dog owner, I would start with a more mellow breed, then get your Akita later in life, if that's still the breed you want.  JMO