1-2: What Could Go Wrong?
Hit the stairs and sneak around the corner above and either take-out or tie-up the two cops here. I chose to tie them up, since I am working on the Achievement for that, but you can do what you like. Remember that there are other Achievements and game path options that depend on the moral decisions that you make, so you may want to consider that.
The first Neko Cat collectible and second beacon
As you approach the second beacon spot look over the rail and to the right on top of the raised roof in the corner - see that white and gray cat (Neko Cat 1 of 12) waving at you? Right! That is the first cat you need to shoot - so shoot it!
After you place your second set of beacons you go outside and have your first firefight - this is more of the tut basically and the aggro system is explained to you. You can play with your sniper rifle here and your other weapons just to get used to them, but once you pull enough aggro your partner will go down below and mop-up the resistance rather quickly.
Move down and across this area to the elevator grate and assist your partner in opening it, and once you pass through and along the hallway here, the Co-Op Choices system is explained to you - and then you exit the building and JB asks you to cover his back while he completes the assignment - and Alice contacts you with some additional information.
The extra task for this contract is to eliminate JB - and you have to decide if you are going to do that or not. If you choose to kill him, you get a CS in which you do that, and the Achievement/Trophy Pessimist. If you choose not to kill him, you get a CS and the Achievement/Trophy Optimist. If you want to earn both of these, pick the one you do not want attached to your play-through and get it, and then re-load your last checkpoint and do the one you want attached to your play-through.
As the mission ends you get treated to a graphic-novel like set of images for the transition that tells the story of what happened after this point - if you chose not to kill JB you see the last few weeks of his life... And his death at the hands of an assassin. Bummer. Next you get a CS in which you learn what those beacons were for. Man, I was not expecting that!
Collect second radio
You need to get off of this roof and out of this building - but the incoming attack and the damage to the building are the least of your problems at the moment - as you head through the damaged wall to the exit door grab the radio on the table (Radio 2 of 14) - look for its glowing dial.
Now help your partner open the grate and you see in the CS that there is an entire squad of masked mercenaries and you are their assignment! God I love this game!
When you take out the bad guys do not forget to pickup anything that they drop - like money and kit - and keep your situational awareness hiked - staying frosty means not taking a round, and that is always a good idea.