Walkthroughs for custom maps.

(I read the relevant thread, which was closed due to an argument :D).

I remember how the person who started that argument was willing to pay $200 to anyone who could complete the "First Blood" map in under 3 months. But then, as expected, he disappeared. :D

Is there a way to see which heroes can be carried over to the next mission in a campaign? I haven't really had to dig into the campaign editor before.

In the campaign editor, when you click on a piece of the map, it should be visible. I usually tested these things using a win cheat (or the code nwcredpill).
You can also break down the campaign into separate maps and view them with the regular editor (just in case someone didn't know).