I think you will have a generic answer on this... (I'll explain this point at the end)
I wish to create silhouettes of still life objects with candle lights... Where are the candles supposed to be placed
Where you want the light. On the oposite side of the place you want the shadow.
and do I need a backdrop?
If you want a backdrop to show in the photo, you need one.
How dark is the room supposed to be?
Depends on that you need. My gess is you need to take the photos on the night.
What are good aperture and shutter speed settings for the same?
The apreture depends on the DOF you want. The shutter speed depends on that aperture, the light and the ISO you choose.
Why my answers are that obvius?
Becouse you need to experiment! You already have some notions about photography. USE THAT KNOWLEDGE! You don't live in a film era, where each photo needed to be done right without seing the results untill some days later. You can see the results right on the moment.
Take a shoot, see the results and make a decision!
If you have a black image move your settings.
The only generic obvious tip I can give you is, use a tripod.
My only "do" I can tell you is TAKE SHOOTS AND EXPERIMENT!
My only don't is Don't stop experimenting.