They don't get spells until 6th level. So, at 6th level, are they considered a 1st level caster, or a 6th? Is caster level determined by class level directly, by class level -5, or by some division of class levels?

I'm curious about this, and I'd like to calculate how spells like Draw Upon Holy Might work out for higher level Paladins.

As far as I know they are considered the actual level they are. So 6th level paladin is 6th level caster.

Not 100% sure though.