Yes, many children under 10 years old will enjoy this game, though some of the strategic depth may go over their head. The game also includes rules for younger players that remove some of the more complicated aspects of the game. You can also choose to remove the symbol and region cards and not count symbol and region bonuses at the end to make the game easier to learn.
The Portal Card is stays in front of you and is never placed in your hand, therefore it never counts toward your hand limit. The Region and Symbol cards are drawn from the Old Testament deck and are placed in your hand. To receive points from them at the end of the game they must still be in your hand, so Region and Symbol cards do count toward your hand limit.
No. You can never be in the same location as another player.