Are there any rules on the positioning adverbs should take in a sentence?

When an adverb modifies a verb, you can usually put it either before, between, or after:

Adverb = 'often', verb = 'go'

Before:

Often, I go for long walks.

Between:

I often go for long walks.

End:

I go for long walks often.

These aren't all equally common; you would probably find the between position used the most.

In your example, you are asking a question, so the 'before' position can't really be used.

Broadly, ever wish you could share information?

Just doesn't work.

But the between and end position are equally valid. I would say that, again, the between position sounds best.

Ever wish you could broadly share information?

The positioning of the adverb should be based on the type of impact our sentence/question needs to make.

The first sentence:

Ever wish you could share information broadly?

This would be more effective when used to catch the readers' attention, probably an advertisement/headline where the idea is to make all readers imagine "broadly".

The second one:

Ever wish you could broadly share information?

This probably has more stress on the "information" rather than on "broadly". It would sound more apt in a paragraph, rather than in a headline.

Again, it depends on how the message needs to be sent across. Both options are correct.

I always think the adverb should be placed as closely as possible to the word it modifies. See how I did it in this sentence, with "as closely as possible"?