The attack Dragonfrost (PHB2 pg 139) is a Sorcerer at will attack that is Ranged 10. How ever it also has a special section stating "This power can be used as a ranged basic attack". What difference would this make to using this attack ability in combat? Would using it as a basic ranged attack require the use of a ranged weapon, adding the power to the basic attack?
Note: RBA = ranged basic attack
Being an RBA has no effect on how you use the power.
Dragonfrost works exactly the way it seems like it would from looking at the power description: it's a ranged implement attack that targets 1 creature within range 10.
Being an RBA does affect when you can use the power.
There are a number of ways to grant yourself and/or allies a basic attack (sometimes it will specify a melee basic attack or a ranged basic attack, but in many cases it just says basic attack, which means the person making the attack can choose which). If you have the Dragonfrost power, then whenever you could make an RBA by pulling out a weapon and using your dexterity modifier for the normal RBA, you could instead attack with the Dragonfrost power (which you should do, unless you're carrying a ranged weapon and have a dexterity that's better than your charisma, in which case why are you a sorceror?).