Hi Matthias,
1. All sorts of methods are possible, but I've played in games where people only want to allow 'certain" types or else the attacker gets a free melee attack against the opponent (a carryover from their RM days). The possibilities are: Levitation or Fly spells would enable to defender to move outside of the attackers reach and thus "disengage them from melee". Even with this so called "free attack" rule, their weapon wont reach and they cant be hit. Simple physics stuff - this game is designed to be used with our knowledge of science so just run with what you (the GM) thinks.
2. No, but I believe that any movement faster than a run requires a moving maneuver so it makes it quite hard.
3. Attack Boomerangs are one shot weapons - they do not return. Returning Boomerangs have a more pronounced bend in them and designed for a slower, rounder flight, whereas attacking boomerangs have less of a bend and are designed to cut through the air to hit the target.
4. Yes, Healing hits is based upon their Max Hits/Total Endurance Bonus.
5. Normally we use 5' to 1" and round to 5' increments, but the better way is to use 1" = 3'. The rounding is better and is more in line with 1" = 1 Meter (for modern people). We don't modify initiative though.
Hope that helps!