Congratulations on your upcoming wedding.
I got married on the Silhouette 7 years ago so have some first-hand experience. Celebrity were fantastic and treated us really well through the entire cruise, it was a really special experience. We got married in Murano, I am not sure how many venues they offer but Murano is probably a good place for a small group, there were only 4 in our party.
We took the photo package offered by the ship for a wedding, this is totally different to any other photo package they might offer and it cost over $1K, not sure how much it would be now. The photographer took us all over the ship, it lasted an hour or so, so you get lots of opportunities for photos, and the package included all the photos printed and digital.
The Spa will offer all sorts of packages for you to get looking your finest for the ceremony.
Andy.