Between one or the other, is "om" or "hvis" preferred in sentences like this (and if so, why), or is it a choice?
It's either a choice, or a regional preference. I would've used 'viss'(alternative spelling of 'hvis') and rarely use 'om' in such sentences, but I guess it's more common to use 'om' elsewhere.
Cool. Takk :)
Which dialect(s) would use the "viss" spelling?
Is there a distinction between "vil" as someone wants to do something VS will do something? Seems like the usage could get a bit confusing in some situations unless im looking at it wrong.
Is "bli med" more correct than "komme med"?
It sounds more natural to me, but I believe it's dialect dependent.
They both receive a generous amount of hits on Google.
'bli med' has been more common than 'komme med' in newspapers and books for at least ten years.
is være med not a correct way to say come along? I have been listening to Pimsleur audios while working and that's how they've been putting it. i.e. Vil du være med?
I think that probably means something more like, "will you be with" rather than "will you come with." So one implies that you're going somewhere, and the other doesn't.
But bli med is literally "become with", so also doesn't imply any action, at least in English.