Here are the answers:
Muscular endurance
50-70% 1 rep max
Bicep curl 1 rep max = 30lbs
How much weight should I use for my curls?
50-70% of 30lbs is 15-21lbs
Muscular strength
70-85% 1 rep max
Bicep curl 1 rep max = 30lbs
How much weight should I use for my curls?
70-85% of 30lbs is 21-25.5lbs