Demolition charges

Can be fired in the same turn when placed in target or in next turn and need again order 'engineer' ?  How close unit have move to target to place charge? Only unit with special rule egineer can use demolition charges, right? I ask because some assault pioneer squads has demolition charges and special rules enginner and some have charges and no special rules (barbarossa, blitzkrieg)

All units with demolition charges are considerd to have the (engineering) ability to use them. A charge must be placed in contact to the target. You may blow up the charge in the same round it was placed or on a later turn, without needing a further order to do so. The engineers placing the charge are unaffected of the blast, unless they are inside the target they blow up. So stay outside the house you want to blow up.

Greetings
Wolflord

In destroyed building unit receive hits 5/4+ but unit make test for cover as usually?

From the rules: "In any turn after the charge is set it can be detonated."