Hey all,
With the re-release of Space Hulk, I thought I'd bring this back from the depths, as it remains fully compatible. To answer some (very old!) questions:

Mission 1 - the North East portion of the map (ie all the bits joined by the 3rd tier entry points) seems rather pointless. 2HT has a direct route to the Patriarch (and hopefully kill it) and then needs to last several more turns. There is no need for him to wander off up there as he will be no more survivable, he'd be better off saving APs and CPs to pick off stealers whereever he kills the Patriarch. Similarly, the stealers have no requirement to use the "3" entry areas as the connecting corridors behind 2HT can be reached from the "2" entry areas. I'd suggest that 2HT starts as far as possible from the Patriarch (or have him chase the Patriarch across the map) and have a more defensible place to see ot the remainder of the game.
This area's there so the genestealers have a place to bottleneck Two Heads Talking basically forcing him to waste his psychic points before facing the Patriarch.

Mission 4 - for clarity, does the Sergeant get the +1 combat bonus? +3 total with lightning claws...
Yep! It's not quite as nasty as it appears, as the bonus only applies to the front.

Also, the victory conditions need clarifying...I'd hope that the marine player survives every game, even if his marines don't! Is it the whole squad, or just a single marine who survives, etc.
Heh heh that wording's just for consistency with the main rulebook. Only a single marine need survive.

Mission 5 - to make it fair on the "non-campaign" version, you should assume that some of squad Marius (say 2 marines) are killed in the previous mission.
A nice little addendum.

Additionally, in mission V, what point does the marine player evacuate from? Is it the marine entry zones or the ladder marked "A" (or am I being stupid and missing some text!)
Nope, me being dim and not specifying. The marines exit from the square marked A (it's a ladder).