A gonarch could've been in the church, "Brother, the devil himself has taken root inside a holy sanctuary, you must banish it from here or your fate, and mine, is to remain here for eternity, the tide of that which corrupts my concregation will never end until the beast is gone from Ravenholm"
I think the supression field makes people infertile, so I think they could still have sex, just not reproduce. People play jokes using dead headcrabs and pretend to be a zombie, then be prompty shot in the head by their mates.
Scientists have already been to Xen collecting samples, I'd assume they'd be trained to use weapons since Xen is full of very dangerous and aggressive wildlife.
It's the deactivated rollermine from when you play with the gravity gun with dog. It can be used as a normal grav gun projectile, to distract enemies (it rolls towards you / enemies (enemies take priority) and distracts them) and it will kill headcrabs by rolling over them.
The balcony (open cell mentioned by nutt) is the easiest I find. Build a staircase from crates, take 2 turrets up and position them, then with the third you can take it up or leave it on the ground floor. Then you hide where the combine can't shoot you, keeping the grav gun on for manhacks (2/3...
The portal storms threw Xen lifeforms to Earth, people migrated to the cities to be protected by the military. The Combine then attacked after preparing, with everyone handily in several small areas the victory would have been easy for them. 7 hours could be accurate as Combine forces would only...
You should have a stalker / half-transformed combine which gurgle as they choke on their own blood while staggering towards you, puke up blood with strange a green algae-like substance in onto you, covering most of the screen so you can only see it attempt to grab onto you as it's dragged...
It would be funny if you could get a dead headcrab, put it on your head and chase the rebels around :D Also a headcrab shooting gun owuld be cool (wish you could pick them up with the gravity gun not just shoot them with the beam)
I know where you mean, if you shoot the helicopter enough it will fly off for a while, get onto your airboat again (it's quicker to go on the little path by the tower and then swim to airboat) and go through the gate. You can't properly destroy the helicopter until you reach the dam just before...