1. Units never block the line of sight of other units.
2. It’s playable by email; check the subforums here.
3. As long as a unit has dice at a particular range it can attack at that range; infantry don’t prevent a tank from firing.
4. The turn alternates between players:
Player A moves
Player B moves
Player A places aircraft
Player B places aircraft
Player A airstrike
Player B airstrike
Player A assault
Player B assault
Casualty Phase
5. It’s during the Casualty phase that counters are flipped and/or removed.
Most things such as turn order and casualty phases are fairly clearly described in the rule book; I suggest looking here for them (newest version of the rulebook): http://www.wizards.com/avalonhill/rules/AAM_RuleBook.pdf
Turn Order page 11
Casualty Phase page 12