Stylistically is it acceptable to include equations and formulae in a literature review?
If the equation is important and not trivial knowledge (this can be debatable based on readership, especially in interdisciplinary work) there is nothing wrong with including it in a literature review (properly cited).
When in doubt, cite more than needed in the draft, as cutting down later will be easier than finding the reference again later.

The same goes for important illustrations/figures - for example of a reaction mechanism in chemistry.

Some people actively like to have equations or figures in the review as it provides a visual break in the text which can make reading easier.
Having said that, attitudes will differ based on subject field, country and just whoever reads it.