I love the name but I think it's too related to Romeo and Juliet. Otherwise I'd definitely use it. It's such a nice name.
No, I don't think it will ever be common and I've never heard anyone named Romeo (other than Romeo from Romeo & Juliet).
I think that a Romeo can come from anywhere but maybe more likely to have an Italian background. Not necessarily though. It's romantic but it's definitely not too wimpy for a boy - I actually think the opposite.
I pronounce it Ro-MEE-oh.