As for Strafe vs Multi: BOTH!
A Frostmaiden tries to load up on +skills and +bow skills (on top of IAS and all that), so with a minimal investment (1 point even) in both of them, you can use each effectively throughout the game. Each has it's uses in different occasions, I'm sure you've used both of them and seen for yourself.
Freezing Arrow is powerful enough to be a main killing skill, especially when coupled with Pierce (and Razortail belt).
You can even have enough skill points left over to max Strafe, if you wished. That way you can have both a strong Cold damage attack, and a good Physical damage attack too.
And yes, Ice Arrow, the level 18 skill, isn't worth more than 1 point as a prerequisite. You can use it between levels 18-30 for taking things down, but after level 30 you wont look back.