I think they all need that thing to screw onto. I don't know about the size.

What finish are you going with? I just caution that you check samples as Baldwin finished do not match other hardware manufacturers.

No idea. Are you having your doors bored on site I assume? That is a non standard size. Ours were supposed to come in non bored but we had to send them back as they were prebored (their mistake). I guess they ran it through the machine to do the hinges and they did the door knob bore also.

I wouldn't think the parts would interchange but maybe I am wrong. I would buy both and see.

As far as that small backplate goes in Baldwin - it usually goes with the smallest Baldwin knob. I am not sure how it would look with a standard size knob - funny perhaps? Also I don't know if the knobs would be interchangeable.

We did a slightly larger rosette (the other felt too small with the small knob) and a slightly larger knob but smaller than standard size - by Omnia. You might want to see if they have something you like. Their traditions line is well priced.

The reason you can buy just the roses on the baldwin is that the baldwin estate is mix and match - chose your knob and backplate seperately for a custom look.

I would also worry about finishes matching. I would want the knob and the rosette to be from the same manufacturer I think.