If you fail to disarm the bomb, does the monorail line ever get repaired over time?

When will people learn to put spoilers in the spoiler section. :facepalm:

No, it doesnt.

As the Colonel noted, if you are going to take the trouble to put a 'Spoilers' notice in your Title, why not just post in the Spoilers Forum?

Do you need a certain explosives skill to disarm the bomb?

Yeah I think it's something along the lines of 45 science and 35 explosives.

Or you could use the activation code.