While responsibility is quite important when owning your own guinea pig, maturity may be just as important.
I know you said you won't lose interest, but there is a chance that you will. Day in and day out, it gets tiring to feed and care for a guinea pig for as long as seven years, especially with social activities, extracurriculars, and other outings heading your way as you get into high school. Even though you have wanted a pig for a long time, you may find that you do not enjoy the care as much as you thought you would. Please do not get upset - I am only trying to warn you that there is a lot of work involved and there is a possibility you will end up losing interest.
Yes, your mom will be home all day, but that doesn't mean she will be with the guinea pig at all hours. Like most moms, she has stuff to do - house cleaning, shopping, and other activities that will limit the amount of time she can spend with a guinea pig. You can't rely on her to be the companion to the guinea pig. While a human's company is so very important, a guinea pig NEEDS a friend for those times when you're just too busy. You will get busy and there will be days when you won't be able to spend as much time as you would like with your guinea pigs. In those instances, it will be crucial your guinea pig has a friend. It's so much more than just having a friend, though - it is a playmate, someone to talk to (we don't speak their language, remember), and someone to snuggle with. Humans cannot take the place of a guinea pig's friend. In order for your guinea pig to be happy, you need to have at least two guinea pigs.
The basic answer is that both sexes can be bonded into a pair. You can bond a male with a male and a female with a female, there is hardly a difference. Simply stated, there is no concrete answer, since it depends largely on the personality and temperament of each guinea pig.
Similarly, both genders require the same level of care. A male is not going to be easier to care for than a female or vice versa. Males are known for being calmer and cuddlier, while girls tend to be a little more active. However, these are largely stereotypes that have been proved false many a time. You will find cuddly and calm girls, just you will find active and playful boys. Some males need monthly cleanings of their anal sac, which is neither challenging nor time-consuming. Above all else, you need to first consider whether you have two hours or more each day to provide care, feeding, and handling to your guinea pigs.
If you're going to be at school for the majority of the day, getting a guinea pig is not really an option right now. Wait until your parents are 100% agreeing to everything - a C&C cage, two pigs, and the purchasing of high-quality food. Make sure they are ready to pay vet bills, because there will be instances where your guinea pig will need vet care immediately and there will be no time to consider the costs.
Your guinea pigs will not be able to eat the crappy pellets or hay sold at pet stores unless you can find Oxbow. You need to get high-quality pellets and hay such as Oxbow or Kleenmama's, usually sold in higher-end or more specialty pet stores or online. You might not be able to find quality pellets or hay at your local pet store, so there is a bit of an inconvenience there if you will need to go out of your way to find the right stuff.
You can catproof a cage by building a top for it with extra grids. You can zip tie the grid cover to the rest of the cage along the back "wall." Coroplast can be found (broken link removed)(Lissie's link) or at sign shops. The C&C cage site,
here, explains a bit more.
If you haven't already, please check out
Guinea Lynx.