It is revealed in the final chapter that Sai and Ino are married and have a son named Inojin Yamanaka. Sai is the only known male character in the series to take on his spouse's surname upon marriage.
Well, there aren't really a lot of interactions between Naruto and Ino aside from filler, but Ino never really had anything against Naruto and was generally amicable with him. If anything, they're surprisingly like minded individuals.
Currently, it is impossible to reset in-game progress on a game account. You can start a new game by logging out of your current profile, and creating a new one. Now, after you log out of the current account, you will be able to create a new one using the initial email address.
Masteries on your champions are the most important thing to do after 6 starring them, the masteries you pick for your champion can significantly increase the effectiveness of the champions skills and overall damage.
If you would like to continue playing the game, you just need to click the Restore Account button in the letter. After that, your game account will be restored.