Yes
SiG P229 in 357
The Sig Sauer P229, however in certain scenes individuals have used the Sig Sauer P226.i think they mostly use the p226 not the p229 but mabey the p228
Sig Sauer P229
50-550 usd
Look on the frame.
Yes same frame and assembly they will interchange
No. You can get a Sig P229 that will fire .357 Sig, but that is not the same as .357 magnum.
http://en.wikipedia.org/wiki/SIG_P229#P229
Sig Sauer P229
Yes, as long as it is made specifically for the P229/P228.
Sig Sauer P229 and P239 chambered in .40 S&W. Here's the press release from Sig.
You will have to call SIG to find out