1. Doubt it.
2. They're gone. It wasn't firmly established in this week's episode, but last week Rick told them to leave before going all Ghost Lori on them. After his tirade, I wouldn't want to stick around either. "Talking Dead" afterwards confirms that they left, but hinted that it may not be the last we see of them.
3. Pair of tree shears and a little stealth. The only people outside were Axel and Carol gettin' all pre-lovey-dovey, and Herschel going to counsel Rick. Michonne was in the bus. There would've been a big blind spot the tower guy could have gotten through, and the Gove has used this tactic before to position his guys before striking.