(I have no clue why it's in this category.. I wanna change it lol.)
Most, if not all, of your questions are answered in these two books.
The Animator's Survival Kit; $25
by Richard Williams
The Illusion of Life; $35
by Frank Thomas and Ollie Johnston
But in short, you should know about the 12 principles of animation.
12 Principles of Animation; YouTube playlist by Alan Becker
Toonz; $0 (Free; Previous price was $6,000)
Used by Studio Ghibli on Spirited Away and Princess Mononoke, by Rough Draft Studios on Futurama, and by many others.
3D (and 2D) Software:
Blender; $0 (Free) or $10/month (Cloud Service)
As a hobbyist, freelancer, or small to medium sized studio you can use Blender as a low-cost alternative to Maya ($125/month) and After Effects ($20/month).
Blender Grease Pencil 2D Animation Tools
One of the best I've tried is Toon Boom Studio. It's discontinued now, and has been replaced by Harmony Essentials (which I haven't tried). The Spongebob Squarepants movies (both of them) were created using Toon Boom, as an example.
It's subscription-based (as a lot of software companies are doing this now) for $15 a month.
DO NOT BUY ANYTHING, YOU CAN DO IT ALL FOR FREE.
IF you have steam, go to the steam store and find Source Filmmaker, download and install. It is recommended that you have a computer that can run games.
If you don't have a steam account, make one, you can since you are 13 years old.
Once source is installed, use YouTube to help you along your way.
for now I'll point you to a coupla free programs:
And a special interest group:
There are several groups on the web looking to recruit and train kids. By the way I use synfig because I always use Open Source but I hate it.
Youtube has a ton of tutorials. 3ds max is a wdiely used app you might want to try.
Otherwise there are free apps like BLender
ask your mom