well as far as i have heard. one thing that the are saying is the multiplayer maps are not based off the story. which is cool it will bring something new. and make it feel like a new experience. also seems like the will have perks in this one. and of course chief is in it!. and the battle rifle is back. and my guess also is there might be some new aliens in there just my thought, and weapons.
all the sexual themes is if you take the close from a person it shows them in the underwear. alcohol. as far as that goes not much. you can choose too. there are bars. but you do not haft to go in. maybe on a quest but still you can choose to buy it or not. so overall. the game is very clean compared to most