any small umerax or crossman holster
The Crosman 357 is modeled after the COLT PYTHON. If the Python fits the holster, then the Crosman 357 may also fit. Your just going to have to try it.
Was it made for the Colt? Is it someone's old flap holster for a Colt 1917, and your Colt wound up inside? What's the condition of the holster? Too many questions to be answered.
Many holster makers have one or more types that will fit.
Yes
I'm going to guess that you're referring to an inside the waistband holster and an outside the waistband holster. An inside the waistband holster literally fits inside the waistband of your pants, and a outside the waistband holster fits on the outside of the pants, either using a belt or a paddle. The IWB is normally more concealable because it holds the gun much closer to your body, however, many people consider the IWB to be less comfortable.
colt D.A. .38 pat. 9-19-1871
A Browning Hi Power
This website has what you need for you question. http://www.blackhawk.com/product/Sportster-SERPA-Holster,1146,1410.htm
Colt sells them.
a good custom leather holster is great but BlackHawk! serpa line may have one.
100-800 USD
Colt 1911 defender