Victorian Era Sewing?

Weirdly enough, we seem to be heading right into the holiday season. And I have a party to attend which requests Victorian period dress. Now, there is nothing I love more than an excuse to sew something totally frivolous and extravagant. However this is totally out of my comfort zone in terms of time period. But I just know that some of you are historical sewing enthusiasts and experts, right?

I've fallen quite in love with Butterick 5823, with its beautiful bodice and sleeve draping.

Here are my concerns: First, historical accuracy. Now, I suppose if the theme of a party is "Victorian," you really have a wide berth when it comes to that, right? When I think Victorian Christmas, I think Dickens. I have no idea where this Butterick pattern falls in terms of era. It's in the Making History pattern series, but there's no more info than that. Thoughts?

Secondly, fabric choice. The pattern recommends lightweight cottons like voile but I'd really like to do it in something more winter appropriate, maybe a crisp shantung with a drapey silk for the ruched insets. What do you think?

Third, foundation garments. I'm assuming one wears a corset and petticoats underneath this. Overbust or underbust?

This may just be pure fantasy sewing since time is of the essence, but I'd love to hear your thoughts! Have you ever sewn anything from this era? Please share!