I can only answer 2 questions :
1)There's no tutorials for MoW:AS unfortunately .
2)Frontlines Mode : 1 team set up some defences while the other team set up an attacking force in 2:30 minutes . After this time , the attacking force attack the defences of the other team to capture the flags that they're defending .
Assault Mode : 2 teams are fighting for the domination of the map by capturing flags . The winning team is the one that reach the goal , for example , if the goal is 200 then the winning team is the one that reach 200 first .
Combat Mode : 2 teams are fighting . Both must kill the most enemies they can . Almost same thing than Assault mode but there's no flags to capture . The winning team is the one that reach the goal .
Sorry I can't answer the 3rd one , and also sorry for my english , It's not my native language so don't mind if I made grammar errors
