My First Major Project

This is my first Major Project, and currently it's only in the conceptual stage. I need to learn to program, make music, and do spriting before I can even think about putting this plan into action. Likely my first games will be tetris, pong, and pacman clones, for experience before I move up to something of this ambitious level.

Harry Potter RPG: Complete.
A complete RPG style game of the Harry Potter series.

The reason I wanted to do this was the Prisoner of Azkaban game for the GBA was an RPG, and although it was short, and not really feature intensive, it was still my favorite of all the ones I've played so far. I want to take that concept and expand it, both in features, and in content.

Any ideas would be muchly appreciated.

Ideas
Custom Character: After the main game is finished (the HP books) or perhaps even before that, you can create your own character, including physical and non-physical traits (gender, body shape, house, hairstyle, and favorite subject, physical and magical ability, likes/dislikes(which may impact stats, and how they improve)

Learning: You can choose to adventure Hogwarts, or you can choose to go to the library and study, or you can do any number of other things inside and outside of Hogwarts.

Side Quests: There will be many places to go and things to do, and even once you go through the game, there will still be things to do. I hope to make the game as open as possible.

Time system: I'll be making a time system, that the player will have some control over. If they want to slow time down to real time (where one minute in the game is one minute in the real world) they can, or if they are waiting for a certain time, or day, they can speed up the time to something more like thirty minutes in game is one minute in real life.

Re-do system: For people who want to "grind" aka build up their skills, I'm going to implement a secret area, which will let them go back to the start of the year, while keeping their skills. Or for people who really enjoyed that part of the game, so they can play it over again.

Romance: A date sim-esque meter for each member of the opposite sex (or same sex) you can improve through conversation, gifts, and side-quest
style dates or other experiences.

Post-Hogwarts: End of Year Seven seems like the end of the game, but I want this to be an open ended game, so I want there to be something to do after Hogwarts, if not just letting the person go back to whatever year they want and look for secrets and side quests.

Skill System: I'm implementing a skill system similar to Ultima I believe, where your skill in an area grows by practicing. If you study transfiguration in class or in the library, your general transfiguration level will improve. If you practice a certain spell, that spells level will increase. Perhaps over time, if someone predominately practices a certain spell, or a certain branch of magic, the others may suffer, to keep people from becoming masters of magic in all areas, to make it more interesting.