1. Starts at 2.2 obviously

2. They are "just switching platforms" and all character data (currency, levels, items on inventory, items equipped, ...) that are stored server-side on SquareEnix servers remains the same regardless of which platform you're playing.
Only real thing that "changes" is your hotbars/HUD placement/configurations (which are stored client-side) that all will be at default positions/configurations.
This is exactly the same behavior you'd get from playing FF14 on another PC or on another PS3.

3. Yes you can play on JP servers if you have an NA disc/digital license of the game.
But unless you are quite proficient on reading and typing in japanese, you really shouldn't play on JP servers.