Yes, Bo didn't give his pistol to anyone until now (he's offering it to Sally, since Dr. Hausmann is in no condition to use one). Bo also still has his nightstick. I think the misunderstanding was a result of Dave/David confusion. David the trucker still had his own 9mm pistol. Dave the mechanic just has a baseball bat and flashlight, I think.
Now that Samantha's on the roof, she should use Charlie's second rifle. Ashley could use Luke's revolver since Tisha's still out of it. Mitchell and Jimmy can use the spare shotguns (Luke's, and either Earl's or Hammond's).
Yeah, it's a shame Dr. Hausmann's full potential hasn't been realized, but given that her base Sanity is 55 and Stephanie's is 90, this situation isn't unlikely. Stephanie just passed a Sanity roll for seeing the zombies, but Dr. Hausmann would have failed it with the result I got. This has given Stephanie more of a chance to shine, though.
The shelter is problematic, but there's a lot that Bo doesn't know yet, especially since he was unconscious and missed some things. Fortunately, they don't have to decide just yet. If the situation with the skinheads is resolved before they do, the roof will be safe. The problem is that there are already people in the shelter who will probably not have time to get back out before the zombies arrive. They'll have to fight the zombies anyway, and they could use some backup to give them a better chance of winning. Maybe when the people holding the garage retreat, they could fall back to the shelter (the stairs to the roof will have been pulled up by then, and it takes a while to lower them). Of course, if the diner is overrun before the garage (which is likely), the people there might not be able to retreat at all. We may need to reconsider trying to hold it. The shelter is also huge, so there's plenty of room to retreat. Aside from the risk of grenades, the other problem with the roof is that even though the zombies can't get up there, the people on the roof can't shoot at the zombies once they get inside the diner - and they will.
I have a sneaking suspicion there were dead bodies in the shelter, which means zombies are already inside. Also, there may be living people trapped there too, based on the jail cells and screaming.
It looks like Luke has already filled his quota of shots at normal range. He's fired 25 shots (5 groups of 5) at 80%. Charlie is firing in groups of 4, however, and he's only fired three groups at 66%. I'm guessing he doesn't have a scope on his rifle, so he hasn't had the full chance to hit for as long as Luke has. Charlie, however, has fired 7 groups of 4 in all. Since he missed one group due to a jam, he should have 2 more groups of 4 shots coming before the zombies arrive:
http://invisiblecastle.com/find.py?u=Luke+the+Hunter
http://invisiblecastle.com/find.py?u=Charlie+Moon
http://invisiblecastle.com/find.py?u=Charlie