Don't use the & form unless you require it's special effects. If you don't know what those are, you don't need them. I'm not trying to be snarky or a wiseass.

I normally use parentheses around the arguments, in part just to make it clear what is being passed to the subroutine. At times, I omit them, but I can't really articulate the conditions that apply. I suppose aesthetics bear on the decision, but I tend to "err" on the side of ().