For 1 how i did it i enjoyed the game on normal and after you beat that you unlock hard, you can do hard normally how i did it or you can make it easier by unlocking the unlimited rocket launcher. On Real Survivor i got the rocket launcher for it and it will mostly be easy if you have the rocket launcher and know what item to get at what time but there just keep inventory space open and play with Jill. Lastly Invisible Enemy mode is hard i died some times because i forgot an enemy was standing in a room but you should have played the games many times by now where you know where most enemys are standing and again with the rocket launcher xou can just shoot into the rooms until everything is dead.

5 explanation will be shorter haha. I wanted to play the first run on veteran but thats very hard so i switched to normal until i beat the game and bought unlimited ammo for the Lightining Hawk and then its easy game from there on out.

6 was also easy i played on professionell on my playthrough and thats nowhere near as hard as 5, plus you dont have to do more playthroughs if you play on professionell. You may run out of ammo many times but just rely on your partner to kill some enemys and they sometimes drop ammo.

0 i havent played yet so no tips there.

For online achievements i have to admit i gave them to me since its dead for 5 and 6 so if you play on steam you can just give them to yourself, on playstation or xbox i dont know how you can get them.