Well we don't know how sheltered those people were, either. They may not have really had to deal with walkers. As far as the unit getting ambushed, they were distracted and worried about walkers, not guys with M-16's ambushing them.
The way you handle both is the same. Sentries don't stand on their feet in the middle of a field skylining themselves.
I think their position favored visibility so that walkers wouldn't surprise them which screwed them when the Governor had snipers in position. They were focused on the Governor himself at first, and didn't figure out where and who was trying to kill them fast enough, I mean you're fighting zombies for months right? It's easy to be unprepared when ONE guy walks up under a white flag and attacks for no reason. For all they knew there were walkers nearby and the gun fire was directed towards them, also at this point we have to conclude that everyone in the WD universe is suffering from some kind of cognitive impairment, relative to our own, there's just...way too much stupid. We'll call it severe PTSD.
the Governor wasn't going to tolerate any threat to is authority, he can't accept a six or seven man unit trained, disciplined and loyal to each other, into his 73 person town. He seems to have a personal knowledge of everyone we've seen and is developing a cult of personality. having a tenth of his population with conflicting loyalties to each other undermines him.
I am glad to see Merl back, the jury is still out on whether it was him stalking Carol while she practicd her C section.
Michonne is MORE eager to leave the town then to help Andrea recover. Good instincts. She figured out that her weapon is a trophy to the governor and that's NOT a good sign at all. Andrea is letting herself be wooed.
She's slipping though, I don't know why she bothered killing her zombies instead of just backing off and running.
...and btw the Governor's a player, he's got his lady sleeping in his bed while he goes to check out his collection. Personally, I think he's hiding his name because his name would be recognized for some heinous thing but I haven't read the comics so idk.
With regards to the larger issues of zombie infection discussed above, forget zombie infection, the governor's poking cadavors with his fingers, everyones getting soaked in gore, and carol, mehhhh why bother with gloves that are in every medical kit, it's just Herschel bleading all over the place, with his axe severed leg to prevent zombie infection in a neglected prison full of rotting corpses, unemptied trash etc. We're gonna start losing people to Hepatitis O.o