Finishing the barricading job is a good idea. Also note that the snipers on the roof will be unable to hit any targets that make it past them and the mines and onto the balcony, because the roof overhangs the balcony. Stephanie had the same problem in Chapter 1.
The ladder is secured by a rope that has one end tied around its top rung and another tied around the base of the satellite dish. It can be pulled up onto the roof if necessary. The balcony is less dangerous than being on the ground when zombies are attacking, but only the roof is truly secure. However, anyone up there could get trapped if the motel is overrun, unable to shoot at zombies on the balcony or inside the building. Making a hole would provide another way on or off the roof, but it will require time and tools.
@Gonzalez:
Malanowski is free to make any suggestions he likes to Lt. Malone. If he wants to convince her of something, he'll need to roll Persuade.
What Sheen and Cole see is actually the helicopter approaching, Now that Black has taken out the woman on the highway, there is nothing for Sheen to shoot at the moment. Don't worry, though, there will be plenty of things to shoot later.
@Steve:
There is one rifle left in the box: Charlie's Winchester M1894 carbine. This is in fact the same rifle Alice had been using on the roof, which she had given to Luke. Luke then placed it back in the box when he switched to the M-14. There are also more weapons down in the warehouse, and some that have fallen off the roof, though all of them will need cleaning. The weapons list has all the details.