A magic sword is worth all the times it will come in handy during combat. It should only be traded away for something of lasting effect. A lasting safe shelter may be just as treasured.
Yes, but its a well known fact that any adventurer worth their salt will keep the +1 sword and sleep in a ditch.
π = 4
Consider a 5' radius blast: this affects 4 squares which have a circumference of 40' — Actually it's worse than that.