I assume you are using the killteam rules here:
http://heralds-of-ruin.blogspot.co.uk/p/kill-team-rules.html?m=1
If so:
1 - a unit with squad rules acts as a squad as per
40k rules; there are extra rules clarifications in the "special rules" section under "squad".
2 - units within 3" can fire overwatch and countercharge.
3 - assaults can be redirecred by passing a leadership check if he wants to target anything within 3" of his shooting attack.
4 - don't have the missions downloaded