Do tortoises and turtles have a well developed skeletal system?

Answer 1

As well-developed as ours. They're reptiles, so they are structurally similar to mammals, with backbones, major skeletal structures all throughout the body, etc. The backbone in turtles and tortoises are actually fused to the shell in this case, but they're just as advanced skeletally as humans, just a few less bones.

Answer 2

Yes of course. Like most other reptiles

Answer 3

Very well developed!
They have all the bones we have, besides the tail and the shells.