1. It isn't
2. No
3. Yes
4. Yes
5. No

But if you just want to have some fun, it doesn't matter if it is legal. But why remake something when you can make your own new game? Game development is really a creative process-- creating settings, characters, stories, mood, tension. It isn't just programming and modelling.

Why not figure out what it is you like about the game in the abstract sense, then make something of your own using those qualities.