WELCOME! I believe you may have a rogue set of hair straighteners in the wheelarch; the clunking is when they bounce off the wheel and the shudder is the power cord being wrapped around the disc...
AHEM! Seriously - you've changed the caliper and I presume all is well with new brake pads? Did you buy a new brake disc as well?
The caliper was seized on you say. That could mean at some time the brake disc might have got rather too hot and might be warped.. that may explain a shudder when you apply the brakes. Or is the shudder there at any other times?
Diff.