3. If you write 2 for one and 0 for the other, questions will arise again. Are these the points scored in the game? Why 2 points? And if only one game was played, they will think it was a draw and that's 1 point for a draw.
Games in groups are played in a round-robin system in 2 rounds (each team plays each other twice).
No, it absolutely cannot be done that way. It simply contradicts the entire concept of the tournament! Look at what you're suggesting: you're told that a game to 2 wins out of 3 games will be played, and the result will give one of them 3 points, then a second game is played on the same principle, and you say let's make it one game and put everything together.
I won't argue with you, you're the organizer, and do as you want. But if there are complaints about the tables throughout the tournament, it's not the participants' fault, but the table's.